The counterintuitive use of sleep deprivation as a rapid treatment for major depression finds itself squarely in Matt’s spotlight today. He begins by discussing its origins in the 1970s, where one night of wakefulness induced temporary remission in 40-60% of patients, and goes on to note that this effect is fragile, with an 83% relapse rate after recovery sleep, pointing to a paradox where sleep itself may be depressogenic for some.

Matt reviews the neuroscientific explanations, including the "overarousal hypothesis," which suggests the therapy works by calming hyperactive brain regions like the amygdala. The episode also covers chronotherapy's role in extending these benefits before presenting a modern conundrum: a 2022 meta-analysis that challenges the standalone efficacy of sleep deprivation, pitting decades of clinical observation against rigorous scientific review. This sets the stage for a scientific reckoning, where the dream of a fast-acting cure confronts the sobering reality of modern evidence.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.

Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.

A third sponsor this week, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

Matt delves into Heart Rate Variability (HRV), the subtle variation in timing between each heartbeat. He explains that a healthy heart is like a "jazz drummer," not a rigid metronome, and a higher HRV reflects a resilient body that can adeptly balance its stress and rest systems. This episode unpacks the science behind HRV and explores the actionable strategies you can employ to improve this critical marker of your overall health.

Matt then explores the key lifestyle factors that significantly influence your HRV. He highlights sleep as the most powerful tool for nightly recalibration, explaining how even moderate sleep loss can suppress HRV. The discussion also covers how exercise, especially HIIT, boosts adaptability, and how stress management techniques can calm the system's "static noise." Finally, he touches on the importance of a consistent circadian rhythm and avoiding substances like alcohol to protect your heart’s healthy variability.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Craving more energy, better metabolism, and immunity? Discover Pique's Nandaka, a ceremonial cacao superfood blend for calm, sustained energy without the crash. Thanks to this wonderful podcast partner, you can now get 20% off for life at pique.com/mattwalker using code MattWalker.

In a supplement industry where trust is critical, Matt uses podcast supporter Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.

Another partner, AG1, is one that Matt relies upon for his foundational nutrition. Their new science-backed Next Gen formula features upgraded probiotics, vitamins, and minerals. Start your subscription today to get a FREE bottle of Vitamin D3+K2 and 5 free travel packs with your first order at drinkag1.com/mattwalker.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

In this latest AMA instalment, Matt and Dr. Eti Ben Simon begin by discussing environmental influences on sleep. The conversation covers how high latitude and prolonged daylight disrupt circadian rhythms, with Eti sharing her own personal experience. Together, our duo shares strategies for managing light exposure and regulating core body temperature with methods like warm baths. The episode also offers evidence-based approaches for shift workers, including strategic napping and forward-rotating schedules.

The discussion then shifts to internal mechanisms, debunking the "sleep before midnight" myth and emphasizing alignment with one's chronotype. The role of the thalamus as a sensory gate for blocking pain during sleep is detailed, with Eti noting that meaningful stimuli can still break through this barrier. Finally, the use of Gabapentin is examined, outlining its limited efficacy for primary insomnia versus conditions like restless legs syndrome.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Partner of the podcast, AG1, is one sponsor that Matt relies upon for his foundational nutrition. Their new science-backed Next Gen formula features upgraded probiotics, vitamins, and minerals. Start your subscription today to get a FREE bottle of Vitamin D3+K2 and 5 free travel packs with your first order at drinkag1.com/mattwalker.

Another of this week's sponsors, David, is a revolutionary new protein bar developed with Dr. Peter Attia. It boasts an unbeatable ratio: 28g of protein and 0g of sugar in just 150 calories. Incredibly satiating with six amazing flavors, it’s perfect for muscle health. Buy yours today at davidprotein.com/mattwalker and buy 4 cartons to get a 5th FREE! If they’re not already sold out, you can also find them at a local store using the store locator—or on Amazon.

Our third sponsor this week, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!

As always, if you have thoughts or feedback you’d like to share, please reach out:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

Eti: X @etoosh, Instagram https://www.instagram.com/eti_bensimon/,  or email at etoosh@gmail.com

Today Matt’s discussion with  Dr. Craig Canapari continues, delving into the major changes in sleep that a child will go through from the ages of one to ten. This includes how regularity and appropriate sleep opportunities are important for getting good sleep, and potential medical issues that can arise from not getting enough sleep, such as snoring and restless leg disorder. They also discuss when during child development it can be wise to reduce napping and switch to monophasic (single nighttime) sleep bouts, and expectations around the transition from a crib to a bed, which often happens around ages 2-4 years.  

Added to this is a conversation about how to deal with struggles with getting your child down for the night. One effective method is changing the *timing* of bedtime, often trying to make it a little earlier, which can result in more sleep for your child. Dr. Canapari also brings attention to the clear and significant sleep disparities that exist across socioeconomic lines in both adults and children. They emphasize the importance of paying attention to the red flags of behavioral issues, falling asleep easily, and hyperactivity which can indicate insufficient sleep. 

Matt and Craig discuss the increasing use of melatonin as a sleep aid in children over the past decade and address safety concerns, highlighting that it can be an appropriate intervention if used with caution and in conjunction with a behavioral plan. Finally, Dr. Canapari reminds us that snoring in a child should not be ignored. It can be a sign of obstructive sleep apnea, which can be holding your child back. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. 

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Another sponsor this week is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Links for Dr. Canapari:

Book: https://a.co/d/07SDrVn  

Twitter: https://twitter.com/DrCanapari

Web: sleek.bio/canapari

TikTok: https://vm.tiktok.com/ZMemf3exT/

Instagram: https://www.instagram.com/drcanapari/

FB: https://www.facebook.com/CraigCanapariMd/

Today Matt’s discussion with  Dr. Craig Canapari continues, as they delve into the science behind sleep training. Together they cover what it is and when it may be an appropriate technique. Dr. Craig Canipari provides an overview of the different methods of sleep training - ranging from simple bedtime routines, to extinction  (also known as cry it out) - as well as some of the historical context behind the technique, and also the controversies and alternatives. It is such a personal choice, and different people feel comfortable with different methods. Dr. Canipari also discusses time restricted eating for your infant, and the importance of considering the long-term effects of sleep deprivation on parents.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. 

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Links for Dr. Canapari:

Book: https://a.co/d/07SDrVn  

Twitter: https://twitter.com/DrCanapari

Web: sleek.bio/canapari

TikTok: https://vm.tiktok.com/ZMemf3exT/

Instagram: https://www.instagram.com/drcanapari/

FB: https://www.facebook.com/CraigCanapariMd/

Today Matt begins a new series all about sleep in infants, in kids, in teenagers, and in parents. He is joined by Dr. Craig Canapari one of the world leaders in pediatric sleep medicine. Dr. Canapari  has also written a fantastic book on sleep for babies, kids and parents called, It's Never Too Late to Sleep Train. Enjoy the first episode in a new series, with some show highlights below! 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. 

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

 Today's podcast is also supported by biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Links for Dr. Canapari:

Book: https://a.co/d/07SDrVn  

Twitter: https://twitter.com/DrCanapari

Web: sleek.bio/canapari

TikTok: https://vm.tiktok.com/ZMemf3exT/

Instagram: https://www.instagram.com/drcanapari/

FB: https://www.facebook.com/CraigCanapariMd/

On today’s episode, Matt goes beyond the if and the what type of exercise to discuss the when. Which is to say, does the timing of exercise matter when it comes to sleep improvements? Based on his experience working on insomnia, Matt would previously have recommended avoiding mid-to-late evening exercise as the resulting rise in core temperature could harm your chances for good sleep. However, it’s since been discovered that the evidence is quite the contrary, mostly allowing us to abandon the myth of evening exercise as the archenemy of good sleep.

But how late is late? How close to bedtime can exercise be done before things actually break? Studies have shown that exercise 3.5 hours before bed boosts sleep by fifteen minutes and significantly reduces the amount of time spent awake at night, while individuals who did weightlifting or resistance training two hours before bed fell asleep in half the time it would normally take and experienced an almost 20% boost in deep non-REM sleep in the first few hours of the night. Getting even closer to bed, an all-men study showed that neither cardio nor weight/resistance training ninety minutes before bed did any damage to sleep (though there was no marked sleep improvement either). But at sixty minutes, there was an impact—a reduction in the total amount and overall efficiency of sleep. Therefore, it seems that exercise before bed will more than likely result in very enviable sleep benefits, so long as it’s done more than an hour before bed (and ideally ninety minutes before).

In addition, it’s been discovered that exercising across different times of day can make a difference to the amount of at least three specific sleep features: REM sleep, light non-REM sleep, and time spent tossing and turning awake at night. First, exercising in the middle part of the day (i.e. three to eight hours before bed) is associated with moderately less REM sleep. Second, morning or evening exercise provides the nice benefit of spending less time in less-restorative, light non-REM sleep. And third, working out in the evening (at least three hours before bedtime) leads to more efficient sleep and less tossing and turning.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Today, Matt focuses on how the type, intensity, and duration of exercise affect its impact on sleep. A study of middle-aged adults split its active group into three subgroups: moderate-intensity aerobic exercise, high-intensity aerobic exercise, and moderate-to-intense weight/resistance training. The groups performing aerobic exercise got more beneficial sleep effects, while surprisingly, the greatest improvement was in the moderate rather than the high-intensity group. These findings replicate those from the National Sleep Survey, indicating a Goldilocks syndrome in finding just the right level of exercise to benefit sleep.

Regarding types of exercise, studies show that cycling produces the most robust improvements in deep non-REM sleep. Meanwhile, more mind-body-based exercises provide equal if not greater benefits in sleep quality than traditional forms of physical activity. 

Another factor to consider is duration of exercise. Some studies have discovered that more minutes of acute exercise in a single bout produce larger benefits in several sleep metrics, including deep non-REM sleep, the speed of falling asleep, and the amount of sleep overall. However, it’s also been found that progressively longer bouts of exercise can be associated with a moderate reduction in the amount of REM sleep, though Matt states that it’s such a modest reduction as not to be concerning.

The final element is the intensity of exercise. Early studies found indications that more intense exercise gave a greater improvement in sleep quality, though the difference in improvement was minimal. Later, more comprehensive studies have reinforced this, indicating that it is not necessary to go to the extremes of physical exertion to get most of the sleep benefits exercise provides.

Currently, the reason why exercise promotes better sleep is unknown, but Matt offers several tenable possibilities, including that exercise promotes the release of immune factors and growth hormone. He also suggests a more “out there” explanation in the form of a chemical called brain-derived neurotrophic factor (BDNF), the release of which is facilitated by exercise, and which is known to increase deep non-REM sleep.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today's podcast is supported by InsideTracker, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link.  InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. 

Another sponsor this week is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

This week, Matt goes deeper into the relationship between sleep and exercise. More specifically, does daytime exercise change the stages and types of sleep? Deep sleep is critical for various functions, so anything that can increase it is desirable. Older adults have an inherently difficult time generating deep non-REM sleep; however, a study showed that the amount can shoot up by 40% following a day with modest exercise. Moreover, it indicated that participants’ cognitive functioning was significantly sharper following that night of exercise-enhanced deep sleep.

Exercise in healthy young adults also stimulates a lush increase in deep non-REM slow brainwave activity, up to 50% in the first part of the night. However, that exercise must be more vigorous to see a consistent, substantive, increase in deep non-REM sleep. 

However, there is a footnote to this good news: most of these studies saw a modest but reliable decrease in the amount of REM sleep the night following exercise. This isn’t a surprise for sleep scientists like Matt, who were already aware of some reciprocity between these two types of sleep, which seem to push and pull at each other’s levels. Why this reduction in REM sleep happens with a dose of acute, one-shot exercise and what the consequences are remains unexplored. Matt’s hypothesis is that it occurs because, in many of these studies, the total amount of time in bed is fixed. He suspects that if individuals were left to sleep as much as they wanted, they would sleep a little longer and thereby get the same amount or even more REM sleep.

Ultimately, the question becomes this: is regular exercise effective for maintaining and improving good sleep, or does its potency gradually wear off ? Thankfully, the answer is that regular, consistent exercise does benefit sleep, and the improvements it provides don’t get fade over time. Indeed, a meta-analysis approach teaches us that regular exercise has four persistent benefits, 1) improving sleep efficiency, 2) an increase in the amount of sleep achieved, 3) an increase in the speed of falling asleep, and 4) improvement in the quality of sleep experienced.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Does exercise have an impact on the quantity and quality of your sleep? The National Sleep Foundation's annual poll found that individuals who exercised frequently (defined as three times or more a week) reported sleeping with a higher quality than those who exercised less than once a week.  Exercise has also been shown to increase the release of endorphins, which can improve mood and promote feelings of relaxation, both of which can contribute to better sleep.

As with most things, moderation is key. Overexertion can have negative effects on sleep, so it's important to find a balance that works for you. It's also important to consider the timing of your exercise as engaging in vigorous activity too close to bedtime may make it difficult to fall asleep. On the other hand, some research suggests that low-intensity exercise performed in the evening can actually improve sleep.

Exercise has been shown to lead to longer sleep duration in both healthy individuals and those with sleep disorders, and it may also lead to improved sleep efficiency. One study found that moderate intensity exercise led to a 65% improvement in sleep efficiency, while another found that high intensity exercise resulted in a 34% improvement.

In addition to these benefits, exercise may also lead to deeper stages of sleep and a decrease in the number of awakenings during the night. A meta-analysis of 13 studies found that exercise was associated with an increase in non-rapid eye movement (NREM) sleep, specifically NREM stage 3 sleep, which is the most restorative stage. 

It's important to note that the relationship between exercise and sleep is not a one-size-fits-all scenario. The intensity, duration, and timing of exercise can all impact its effect on sleep. It's important to pay attention to your own body and its unique needs when it comes to finding the right balance of exercise and sleep. Additionally, the optimal amount and type of exercise for improving sleep may vary depending on a person's fitness level and individual preferences. 

It may be helpful to experiment with different durations and intensities of exercise to see what works best for you and your sleep patterns.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today's podcast is supported by biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker.LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

Another sponsor this week is the good people at InsideTracker, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link.  InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Almost every species will suffer catastrophic impairment in the brain and body due to total or chronic partial long-term sleep loss—save for a small handful of befuddling cases where lack of sleep does not cause devastating impairment. While humans are the only species that deprives itself of sleep for no adaptive benefit, there are rare situations where an animal will limit or go completely without sleep. Starvation pushes aside an organism’s need for sleep to forage more widely, while the need to protect newborns can be prioritized over sleep (as seen in the long journeys of killer whales returning to their pods). 

Even more remarkable is the ability of birds to stay awake for thousands of kilometers during migration. The white-crowned sparrow, for example, can withstand days without sleep during their migratory period with no cognitive impairment; it has basically discovered an internal biological Iron Man suit!

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

The final installment of this series focuses on what happens inside your brain during deep, non-REM sleep that allows you to fixate new memories. There are at least two mechanisms at work here. One is a process of shifting information from short to long-term memory. Each night when you go into deep non REM sleep, those long range brainwaves of deep sleep are going to be moving packets of information, from that short term, vulnerable, USB stick-like memory reservoir (the hippocampus) to the safer long term storage site (the cortex). When we wake up each morning, we've now cleared out that USB memory stick, and we've refreshed and restored our ability to start learning new memories. This process repeats, filling up the USB stick with new information during the day, and then at night, transferring those memories over to the long term storage site in the cortex.

The second memory mechanism, memory replay, is very different. Back in the 1990s, scientists recording the activity of individual brain cells in the memory centers of rats running around a maze discovered that different brain cells coded different parts of the maze. More remarkable was the discovery that the sleeping brain would replay these new memory sequences during deep, non-REM sleep much faster than standard waking speeds. This meant the memory trace was being replayed many times, and the brain was repeatedly etching it more permanently into the brain.

There is at least one other time during sleep when we see memory replay—REM sleep, the stage when we dream. But here, memories are replayed at much slower speeds, sometimes just half the speed of waking experience. Because of this temporal distortion - where time within the dream is slowed down and expanded - you will feel as though you have been dreaming for far longer than you actually have. The movie Inception, in fact, draws some inspiration from this concept - almost as though the director and the writer of the movie Chris Nolan had a little bit of idea help from a sleep scientist!

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today's podcast is supported by biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

Another sponsor today is MasterClass - the online streaming platform where anyone can learn from the world's best about a variety of topics such as cooking, art, science, and, of course, technology. When you sign up, you get access to all of the classes taught by such masters as Martin Scorsese, Venus Williams, and Neil deGrasse Tyson, to name a few of Matt’s favorites. You may even find a masterclass from a familiar sleep scientist! This year, Masterclass is offering a special gift for the holidays - buy one annual Masterclass membership and get another one totally free! So if you're curious and have a thirst for learning, head on over to masterclass.com/mattwalker  now.

And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Previously, we learned sleep is necessary before learning to prepare the brain to learn effectively. But sleep is also needed after learning to cement new information in your brain. This discovery happened in 1924 when two German researchers pitted sleep and wake against each other to see which would win out in memory-savings benefit. Their findings suggested that time spent awake can be hazardous to new memories while time spent asleep has fixating benefits.

Researchers have also put REM sleep head-to-head with non-REM to see which is more effective at saving memories. When it comes to memory, it is deep non-REM that helps hit the save button on new memories. These results led Matt to conduct experiments where we causally enhance the memory using electrical or auditory brain stimulation methods, and as a result, boosting the next day retention of memories. Indeed, with some of these sleep-stimulating methods, researchers have been able to double the amount of memory-savings benefit from sleep.

The results of these studies have real pragmatic and clinical implications, including in the context of aging and dementia. It’s no secret our learning and memory abilities begin to decline as we get older, but it’s also been discovered that a physiological signature of aging is that your sleep gets worse, especially the amount of deep, non-REM sleep. Recent evidence indicates that these two processes aren’t simply co-occurring but significantly interrelated. 

The potential silver lining of this is that sleep is something we may be able to do something about. Matt and other researchers are exploring the use of direct current brain stimulation to restore some healthy quality of deep sleep in older adults and those with dementia, thereby salvaging aspects of the learning and memory function. And the tentative answer so far is that this could work, although it will take some years before we can even start to entertain real hope in this regard.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Those fine people at Athletic Greens are one of the sponsors of this week’s episode. and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health and because he did his research on the science and ingredients in Athletic Greens and thinks its science and scientific data that can be taken as ground truth.

Another sponsor this week is the good people at InsideTracker, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link.  InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to Athletic Greens and InsideTracker to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Matt explores the critical link between sleep and Alzheimer's disease today, explaining how the brain’s "glymphatic system" clears toxic proteins like amyloid and tau during deep sleep. He describes how insufficient sleep impairs this process, creating a vicious cycle where protein accumulation damages sleep-generating brain regions and increases dementia risk.

Matt goes on to discuss groundbreaking research on a new class of sleeping pills, Dual Orexin Receptor Antagonists (DORAs), that may enhance this cleaning mechanism. While preliminary human and animal studies show these drugs can reduce toxic proteins and offer neuroprotection, the findings underscore the profound importance of prioritizing high-quality sleep as a powerful, accessible tool for ensuring long-term brain health.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

One of this week's sponsors, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!

Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.

In a supplement industry where trust is critical, Matt uses podcast partner Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

It is a fundamental truth that sleep is far more than the absence of wakefulness. It is an incredibly active state, demonstrated by the fact that numerous functions of the brain and body are restored by and depend on sufficient sleep. One of the most impressive and best-understood of these is sleep’s beneficial role in boosting learning and memory abilities. Sleep is necessary both before and after learning and it intelligently associates and interconnects new memories together, offering the ability for creativity and ingenuity.

The first of these benefits starts while we’re awake, as the brain acquires novel information, and different types of memories are imprinted in different parts of it. Fact-based memories depend on an area of the brain called the hippocampus, which is almost like a USB stick. Some years ago, Matt and his team conducted a study on the hippocampus and found a 40% deficit in the ability of the brain to make new memories without sleep. In addition, scientists working with rats have found that depriving the brain of sleep stops the cells within the hippocampus’ memory structure from forming strong connections. Notably, it doesn’t take an entire night of sleep deprivation to produce these types of impediments—selective deprivation of deep, non-REM sleep in humans can produce the same effects.

Research has shown that during the deepest stage of deep, non-REM sleep, powerful brainwaves combine to act like a transfer mechanism. Wanting to know even more about how learning capacity and ability change across a waking day and how sleep modifies or restores that, Matt and his team designed a new study on daytime naps. They found that staying awake throughout the day resulted in a progressive decline in learning capacity, while those who took a ninety-minute nap showed no such decline. In fact, their capacity to memorize facts increased after that nap, showing a 20% learning advantage. This illustrates further that, without sufficient sleep, the brain is like a waterlogged sponge, our memory circuits saturated with memories so that we can no longer absorb new information and make new memories effectively.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today’s podcast is supported by MasterClass - the online streaming platform where anyone can learn from the world's best about a variety of topics such as cooking, business, art, entertainment, writing, sports, science, health, and, of course, technology. When you sign up, you get access to all of the classes taught by such masters as Martin Scorsese, Neil deGrasse Tyson, Ron Howard, and Bill Clinton to name just a few of Matt’s favorites. You may even find a masterclass from a familiar sleep scientist! And for this Holiday season, if you give one annual membership you'll get a second one, free! 

Another sponsor of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance.

So, make your way over to LMNT and MasterClass to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

It’s been said that sleep is the new sex, and rightly so—a good night of sleep is going to do many things for the vibrancy, intimacy, and vitality of your relationship. We know that when couples are not getting sufficient sleep, they have more conflicts the next day and won’t resolve them nearly as well. This is partly because underslept couples suffer a loss of empathy for each other.

However, insufficient sleep also has an effect on sex itself. Specifically, your reproductive hormones suffer, which are critical for the health of your sexual relationship. For example, young men who sleep just four to five hours a night will have a level of testosterone equivalent to someone ten years their senior.

The same is true for women. Women who are not getting adequate sleep are 30% more likely to have abnormal menstrual cycles and suffer reductions in hormones critical to sexual wellness and fertility, including estrogen, luteinizing hormone, and follicle-stimulating hormone. 

Reductions in estrogen and testosterone can also decrease the sexual arousal a woman experiences. In contrast, one hour of extra sleep is associated with a 14% increase in the likelihood of a woman wanting to be sexually intimate with her partner.

So sleep will certainly enhance sex, but it turns out that sex will also enhance your sleep. Sex before bed will improve the subsequent quality of sleep that you get that night, as long as that sex results in orgasm.

And thankfully, it’s not necessary to have a partner to get these benefits. Orgasm achieved through self-stimulation helps an individual fall asleep faster, and improves the reported quality of sleep they subsequently obtain. 

These findings are potentially important because they tell us that both sex and orgasm seem to be reliable sleep aids. So perhaps we don’t need to look to the latest and greatest sleep gadgets. Instead, we may be able to explore sex and orgasm as potential pathways to better sleep. In summary, sleep and sex are powerful and playful bedfellows.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

A few years ago, a survey by the Sleep Council in England found that 1 in 4 people in a couple would get up during the night and go to another room to get a good night’s sleep. Following that, a report by the National Sleep Foundation in America demonstrated that almost the same number (25%) of couples admitted to sleeping in separate bedrooms. In fact, a more recent anonymous survey found that 30%-40% of couples sleep in different beds. 

Part of the societal stigma (and anxiety for individuals couples) surrounding a “sleep divorce” is the incorrect assumption that if you’re not sleeping together, then you’re not *sleeping* together. Because of the negative connotations, the world’s leading export on the topic, Dr. Wendy Troxel, has suggested renaming it a “new sleep alliance.” Whatever we call it, though, it seems clear that more people are admitting to sleeping separately. Of course, sleep divorce isn’t for everyone. Some couples feel safety and security when co-sleeping. 

The science is rather clear. On average, couples do not typically sleep as well with a partner next to them as when they are alone. When one person moves in their sleep, there’s a 50% chance that their partner will wake up or suffer worse sleep as a consequence. Moreover, the sleep-stage quantity and quality of that sleep is objectively worse across numerous metrics when sharing a bed relative to sleeping alone. 

However, there’s an interesting twist in this tale of co-sleeping: despite sleep being objectively worse, couples will often say they still feel more satisfied overall with their slumber experience when they are sleeping in the same bed. 

All of which begs the question of what are we to do here? Matt offers four actionable suggestions: 1) be honest with yourself about your sleep needs; 2) have a gentle, honest conversation with your partner about your sleep needs as a couple; 3) suggest testing out your agreed new sleep arrangement for a period of time; and 4) try to retain much of what you would get by sleeping together while you’re sleeping apart. By this, Matt means the bookends of sleep: the saying good night and good morning. It’s a small price to pay for both partners getting great sleep at night, which will also improve your relationship.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today's podcast is sponsored the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance

Another sponsor today is MasterClass - the online streaming platform where anyone can learn from the world's best about a variety of topics such as cooking, business, art, entertainment, writing, sports, science, health, and, of course, technology. When you sign up, you get access to all of the classes taught by such masters as Martin Scorsese, Venus Williams, and Neil deGrasse Tyson to name just a few of Matt’s favorites. You may even find a masterclass from a familiar sleep scientist! 

So, make your way over to LMNT andMasterClass to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Cognitive Behavioral Therapy for Insomnia (CBTI) can be split into at least five core components: 1) sleep restriction therapy, 2) sleep hygiene, 3) stimulus control, 4) cognitive restructuring, and 5) relaxation therapies. 

Sleep restriction therapy has been shown to be one of the most effective components of CBTI. It  isn’t about restricting your sleep so much as limiting the amount of time you are allowed to spend in bed, and it aims to drive up the brain’s appetite for sleep, and promote long bouts of unbroken sleep. 

Sleep restriction works by targeting the natural buildup of adenosine in your brain. Limiting time in bed through sleep restriction means you are awake longer, and the longer you are awake, the greater the build-up of adenosine. After several nights, sleep restriction helps you build up a wonderfully healthy amount of sleepiness that allows you to fall asleep more easily, and stay asleep soundly across the night. Because sleep restriction helps with building sleep pressure, it increases your sleep efficiency, meaning that you sleep almost all the time you’re in bed even though you’re in bed for less time overall. Once your sleep has stabilized, your clinician will start to add back more time that you’re allowed in bed.

The second component of CBTI is sleep hygiene, covered in the previous episode all about sleep optimization The third component involves teaching relaxation methods, such as stretching, breathing, and meditation. 

The fourth component is cognitive restructuring, which involves your clinician helping to disrupt and scientifically disprove your misbeliefs and anxieties around sleep.  The fifth component is called stimulus control, which means not laying in your bed fretting and catastrophizing. Stimulus control seeks to help you gradually extinguish the bad associations you may have with your bed/bedroom.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Those fine people at Athletic Greens are one of the sponsors of this week’s episode. and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health and because he did his research on the science and ingredients in Athletic Greens and thinks its science and scientific data that can be taken as ground truth. 

Another sponsor this week is the good people at InsideTracker, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link.  InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over toAthletic Greens and InsideTracker to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Very understandably, many insomnia patients try to self-medicate their condition with varied “sleep aids”. The tragedy us that most of them not only fail to help but actually make insomnia worse.  

Most common among these is alcohol, which hurts your sleep in at least three different ways: 1) it sedates your brain, rather than generating naturalistic sleep 2) it increases the frequency of nighttime awakenings and makes it harder to fall back to sleep, and 3) it inhibits REM sleep.

THC also inhibits REM sleep, and users can develop a dependency on and tolerance to it, requiring more to get the same sleep effect. Worse still, THC is associated with a severe withdrawal insomnia, which only leads to relapse use. 

Another ineffective tool is melatonin. Melatonin does not help people with insomnia sleep, as we discussed in the episode all about Melatonin. 

The other option is classic prescription sleeping pills. However, based on their safety concerns and their minimal effectiveness long-term, the American Academy of Sleep Medicine and the American College of Physicians (ACP) now state that classic sleeping should no longer be the first-line treatment for insomnia. Instead, the first line treatment for insomnia should be the non-drug approach called cognitive behavioral therapy for insomnia (CBTi), and the one that Matt typically advocates for.

At a high level, CBTi involves working with a trained clinician for several weeks to change your habits, behaviors, mental beliefs, and stress around sleep. Many people with insomnia lose all confidence in their sleep and have terrible anxieties around not sleeping—in other words, their sleep controls them, and CBTI is designed to reverse that. 

Many clinical studies have shown that CBTi is just as effective as sleeping pills in the short term yet has no negative side effects. Unlike sleeping pills, its benefits can last for many years after stopping work with your therapist. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today’s podcast is supported by MasterClass - the online streaming platform where anyone can learn from the world's best about a variety of topics such as cooking, business, art, entertainment, and, of course, technology. When you sign up, you get access to all of the classes taught by such masters as Martin Scorsese, Venus Williams, Gordon Ramsay,  and Bill Clinton to name just a few of Matt’s favorites. You may even find a masterclass from a familiar sleep scientist! So if you're curious and have a thirst for learning,  head on over to masterclass.com/mattwalker and you will get a discount when you sign up.

Another sponsor of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. 

So, make your way over to LMNT and MasterClass to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Some of the first neurological-related discoveries about insomnia were made by placing healthy sleepers or patients with insomnia inside brain scanners, and measuring changes in the activity in different parts of the brain as they tried to fall asleep. In the good sleepers, three main regions of the brain started to shut down at sleep: 1) emotion-related regions, 2) basic alertness-generating regions, and 3) the sensory awareness gate of the brain.

There were also changes in the functional connectivity of large-scale networks in the brain. In patients with insomnia, the functional connectivity between these networks changes differently. Specifically, two large-scale networks show abnormalities in patients with insomnia: the default mode network, associated with ruminating and thinking about the past and future; and the salience network, associated with detecting threats and instigating changes in mood and emotional reactivity. These two areas become overly communicative and too tightly bound up together in their ongoing chatter of connectivity in patients with insomnia. Once again, this can lead to excessive worry, rumination, and emotion and a feeling of being under threat.

Matt has previously mentioned how patients with insomnia can have an excessive release of stress-related chemicals. Those chemicals can also flood the brain, causing excessive activation in all the stress-related regions described above. Critically, though, it’s a reciprocal relationship—if you have hyperactivation in those parts of the brain, you can also trigger the body to release those stress-related chemicals. This becomes a self-fulfilling, negative-spiral prophecy where, as each response increases, further stress-related brain and body activation occurs. 

These measurable changes in the brain and body teach us that insomnia is associated with a specific, and quite complex, set of changes within the brain and the body. No wonder the blunt instruments of old-school sleeping pills are yet to be the ideal way to treat insomnia.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens , and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Today’s episode focuses on changes within the bodies of people suffering from insomnia. Almost all forms of chronic insomnia come with a significant psychological component, namely emotional distress and anxiety. This starts a Rolodex of anxiety spinning once you turn off the lights. This leads to rumination and catastrophizing, which will thwart any hopes of a good night’s sleep.

Since psychological stress is one of the principal triggers of chronic primary insomnia, researchers went in search of the underlying biological cause. We found two culprits. 

First was an overactive state of the sympathetic nervous system. Under normal circumstances, it will occasionally switch on in response to a threat, kicking off a cascade response which increases your heart rate, blood flow, and metabolic rate. However, a chronic elevated flight or flight state, as occurs in insomniacs, has damaging biological consequences. A racing heart and raised metabolic rate lead to a raised core body temperature, when exactly the opposite is necessary for good sleep. 

Second was the discovery of an excessive amount of activity in the adrenal cortisol-producing system (called the HPA axis) in insomniacs. When you experience a chronic state of stress, worry, and anxiety, that adrenal stress HPA axis instigates a chain of command response, resulting in the release of the wake-promoting hormone called cortisol. In good healthy sleepers, cortisol levels normally hit their lowest levels right at the point they’re falling asleep.

In insomnia patients, cortisol levels do start falling early in the evening. But then, they spike back up right at the point of bedtime. Later in the middle of the night, we also see cortisol levels once again spike in insomnia patients. These two spikes seem to overlap with the two main flavors of insomnia: sleep-onset and sleep-maintenance. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Sponsoring today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. 

Another sponsor of the podcast this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now because he’s serious about his health, and because he did his research on the science and ingredients in Athletic Greens and thinks its scientific data can be taken as ground truth.

So, make your way over to LMNT andAthletic Greens and take advantage of these incredible deals. As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Today’s episode takes two questions as its subject: first, why does someone develop insomnia, and second, what adds gasoline to the sleep-disorder fire of insomnia and only makes it rage more powerfully? These are two very complex questions, but through lots of great science and wonderful scientists, we now have a conceptual model explaining how you may find yourself falling into the pit of insomnia. This is called the “3-Ps” model, and it consists of a three-step knock-on cascade of factors that lead to insomnia: predisposing, precipitating, and perpetuating factors.

Predisposing factors are those that make a person more vulnerable to insomnia, a good example being certain types of genes that play a non-trivial role in your risk of developing insomnia. It’s been discovered that insomnia shows a genetic heritability of between 28%-45%, so if one or both of your parents had insomnia, there is a predisposing risk of developing it. This is not, however, an absolute guarantee that you will develop the condition; these genes simply make you statistically more predisposed. Instead, something else has to come along to flick the first domino that causes the chain reaction development of insomnia.

This inciting flick is what the second P—precipitating factors—refers to. The word “precipitate” comes from the Latin root praecipitat, meaning “thrown headlong into something,” which is a good description of what a precipitating factor is—it’s a trigger that pushes you headlong into this thing called an insomnia disorder. Examples of these factors include bereavement, bad breakups, and stress at work, all of which can push someone over the threshold of developing insomnia.

The third P—perpetuating factors—can also be understood through its Latin root, perpetuus, meaning “to continue or make permanent.” Perpetuating factors are those which continue the condition and make it even more permanent. They include examples of poor sleep hygiene like drinking too much caffeine during the day or using alcohol or THC (which is involved in cannabis) as a sedative in the evening. Of course, it’s completely understandable that someone suffering from insomnia would reach for the crutch of alcohol or THC, but they are now understood to be perpetuating factors that only make matters worse.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today’s podcast is supported by MasterClass - the online streaming platform where anyone can learn from the world's best about a variety of topics such as cooking, business, art, entertainment, writing, sports, science, health, and, of course, technology. When you sign up, you get access to all of the classes taught by such masters as Martin Scorsese, Venus Williams, Gordon Ramsay, Steph Curry, Neil deGrasse Tyson, Timberland, Ron Howard, and Bill Clinton to name just a few of Matt’s favorites. You may even find a masterclass from a familiar sleep scientist! So if you're curious and have a thirst for learning,  head on over to masterclass.com/mattwalker and you will get a discount when you sign up.

So, make your way over toMasterClass to take advantage of this incredible deal. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

There is no quick test that can determine insomnia. Instead, the diagnosis of clinical insomnia disorder is based on a set of clinical assessment and interviews. These center on three core features: 1) difficulties falling asleep, 2) difficulty staying asleep, or 3) waking up and not feeling refreshed by your sleep.  Furthermore, to receive the diagnosis, you often have to be experiencing these things at least three nights per week; and having these issues for three straight months.

One meta-analysis looked at over twenty studies of people with insomnia or healthy sleep. It found far fewer differences in their sleep recordings than you would imagine. The insomnia patients did spend more time awake, and there were reductions in their deep non-REM and REM sleep. But none of the differences  explain the degree of suffering for those with insomnia. 

This mismatch can be illustrated by an extreme example. There is a rare variant or subtype of insomnia called sleep state misperception. It is characterized by a mismatch whereby the patient reports their sleep as very bad. But the sleep recordings show a different story. The recordings show that the patient has slept a full, normal night of sleep, but the patient will tell you that they felt as though they never slept a wink! 

Such patients used to be dismissed as having nothing wrong with them. Now, science and medicine no longer take this view, and instead, understand that there is a mismatch going on, that the patient has a misperception of their sleep, and they still require clinical consideration.

So, that’s an overview of insomnia classification and diagnosis. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram. 

Today’s episode is the first in a 7-part series on insomnia. Matt starts with a calming reality—insomnia isn’t a single bad night or a string of bad nights of sleep. In the US, epidemiological studies have suggested that insomnia disorder is as prevalent as the obesity epidemic: around 10-15% of the population suffer from clinical-grade insomnia, making it the most common sleep disorder. Indeed, one out of every two people will experience insomnia during their lifetime. It is therefore very likely that you or someone close to you is suffering from insomnia.

But what is insomnia? There are perhaps different “flavors” of insomnia, although it depends on the clinical criteria used by different countries. One useful way scientists and doctors have thought about it is on the basis of three different features: 1) sleep-onset insomnia, 2) sleep-maintenance insomnia, and 3) non-restorative sleep. These features are not mutually exclusive.

Clinicians often use the 30/30/3 “rule of thumb” to first distinguish the possibility of insomnia. The 30/30/3 rule means the following: 1) it takes you at least 30 minutes to fall asleep,  or 2) 30 minutes go fall back to sleep after waking during the night, and 3) that this is  happening consistently at least 3 nights a week.

Insomnia is *not* sleep deprivation. Sleep deprivation is  defined as having the sufficient ability to generate sleep, but insufficient opportunity to get it. Insomnia is the opposite of this. Insomnia is the insufficient ability to generate good quality or quantity of sleep, despite having sufficient opportunity time to sleep.

Finally, Matt points out that insomnia can be a standalone condition, or a secondary symptom of something else, for example, chronic back pain.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

One of the sponsors of the episode today is a long-time one, our good friends at the athletic clothing company, Vuori. They, too, have a special deal for you all where you can get 20% off your purchase when you visit vuori.com/mattwalker. Vuori produces really good, high quality clothing, and they offset their carbon footprint 100%, both of which, of course, mean a great deal to me. So, if you like athletic clothing, and you wish to help the planet out, then check them out at vuori.com/mattwalker and get 20% off your purchase. 

Another sponsor of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. So, if you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

 And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Matt and Dr. Eti Ben Simon join forces once again to answer all of your top sleep questions. This time around, they break down the science behind the snooze button, why you might be falling asleep during passive activities like watching TV, and the truth about sleep fads like consuming salt before bed or using "grounding sheets." The episode also explores the frustrating issue of sleep fragmentation - waking up multiple times a night - and why it undermines sleep quality even if you fall back asleep quickly.

Learn how to assess your own sleep quality using key daytime indicators like energy and mood, without needing a tracker. For those struggling with frequent awakenings, discover a powerful, science-backed strategy called "bedtime restructuring" to help consolidate your sleep. The episode concludes with a look at new research on a potential "fail-safe" for sleep induction linked to mitochondrial stress, revealing a new frontier in sleep science.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.

Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.

A third sponsor this week, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt or Eti:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

Eti: X @etoosh, Instagram https://www.instagram.com/eti_bensimon/,  or email at etoosh@gmail.com

Today’s episode focuses on optimising your sleep. It’s designed for people who don’t have clinical insomnia but would like to fine-tune their sleep. Matt goes over five conventional tips, and five unconventional tips that may be new to you. 

The first tip is regularity—going to bed and waking up at the same time every day. Your brain has its own master 24-hour clock, the suprachiasmatic nucleus, which expects regularity. 

Second is temperature—your brain and body need to drop their temperature for you to fall and stay asleep, so the ambient temperature must be cold. 

Third is darkness—we need darkness to trigger the release of melatonin. 

Fourth is to walk it out. If it’s been around 25 minutes, and you can’t fall asleep, get out of bed, relax in another room, and come back to bed later. 

Finally, try to abstain from coffee from around noon and avoid drinking alcohol in the evening.

Of the non-conventional tips, the first is this: if you’ve had a bad night’s sleep,  DO NOTHING. Don't wake up any later. Don't drink excessive compensation caffeine. Don't nap. And don't go to bed any earlier the following night. That explains the reasons why.

The second tip is to have a wind-down routine. Your biology needs to wind down so you can descend into good sleep at night, so we should all find our own wind-down routine.

Third is to stay away from naps, especially after 1pm, which is a bit like snacking before your main meal. 

The fourth tip is don’t count sheep. It doesn't work (in fact, it makes matters worse!) Instead, take yourself on a familiar mental walk. Doing this helps take your mind off itself and lets you fall asleep because you stop overthinking.

And the ffinal unconventional tip is to remove or cover all clock faces in the bedroom. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data can be taken as ground truth.

So, make your way over to Athletic Greens and InsideTracker to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, p&

Matt is back this week with his recurring series, ‘Sleep is Bloody Remarkable’. Today’s episode is all about why we are unique when it comes to sleep. 

When we compare our sleep to that of all other primates, humans stand out in two ways. First, we spend far less time asleep, and second, and in bloody remarkable 😂 contrast, humans get more than double the amount of REM sleep.

Unlike many other primates, we humans are exclusively ground (or bed!) sleepers. In contrast, primates usually sleep arboreally, meaning in the branches of trees. During REM sleep, to prevent acting out our dreams, the brain paralyzes the body. But this is far too dangerous to do if you are sleeping up in the trees, lest you fall fatally down to earth.

Homo erectus, as the first obligate biped and, with fire to deter predators and blood-sucking insects, was able to sleep fairly safely on the ground. However, fire didn’t eradicate all the risks. This forced another [bloody] remarkable change: hominids had to become far more efficient in their sleep and thus shorter duration of sleep. 

This re-engineering of human sleep became one of the triggers that rocketed Homo sapiens to the top of the evolutionary pyramid due to REM sleep’s supercharging of 1) our socioemotional, allowing us to form the cooperative societies that formed the basis of modern civilizations, and 2) cognitive intelligence, particularly our creativity, which was the fuel to our brain-derived engine of ingenuity that helped in the great advances of civilization. 

“Simply put: we sleep, therefore, we are.” 

Sleep really is bloody remarkable. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

One of the sponsors of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. So, if you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase.

Another sponsor of the episode today is our good friends at the athletic clothing company, Vuori. They have a special deal where you can get 20% off your purchase when you visit vuori.com/mattwalker. Vuori produces high quality clothing, and they offset their carbon footprint 100%, both of which, of course, mean a great deal to me. So, if you like athletic clothing, and you wish to help the planet out, then check them out at vuori.com/mattwalker and get 20% off your purchase.   

So, make your way over to LMNT and Vuori to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

In this episode, Matt goes deeper into his exploration of  lucid dreaming. He tells us all about studies demonstrating that lucid dreamers can wake from dream sleep on command, demonstrating control over intention in their dreams, and even bring themselves to orgasm in dream sleep!

Matt tells us about two leading methods for developing the skill of lucid dreaming. The first is Mnemonic Induction of Lucid Dreams, which involves the creation of a conscious, deliberate intention to remember that one is dreaming. For example, repeating a certain phrase each night before sleep. The second is the Reality Testing Method. This involves consistently examining one’s environment and testing to differentiate between which of the two worlds, waking or dreaming, it is. The idea is to ingrain these tests in your waking life, so that they will flow over into your dreams, thereby triggering lucidity if you are dreaming.

But how does the brain become lucid during dreaming? It’s been discovered that when lucid dreaming starts, the prefrontal cortex fires up into activity! This seems to be a defining quality of the lucid dreaming state, different to classical REM sleep dreaming where this rational control region of the prefrontal cortex re-engages, thereby letting you gain volitional control over what you dream.

Matt finally poses this hypothesis: between 80 to 90 percent of the populace are not lucid dreamers. If gaining dream control was so beneficial, surely more of us would do it. However, Matt counters his own argument: as we have not stopped evolving, it’s possible that lucid dreamers represent the next iteration of hominid evolution in their ability to control their dreams, and potentially harness their preferred creative problem-solving ability! #mindblown!

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

In part five of his series on dreams, Matt discusses what lucid dreaming is and how it was scientifically proven to be real.

We define lucid dreaming as the moment when an individual becomes aware they are dreaming. Historically, the concept of lucid dreaming was considered a scientific scam. First, to claim that people can gain conscious control over a normally unconscious process injects a heavy dose of ludicrous into the already preposterous experience we call dreaming. Second, how could any scientist objectively prove a subjective claim, especially when the individual is asleep when they do it?

Well, several years ago, an experiment removed all such doubt. Lucid dreamers were placed inside an MRI scanner and instructed to alternately clench their hands. The researchers took snapshots of their brains as they were doing this, allowing them to define the precise  areas controlling each individual’s left and right hand. In the second part, the participants again underwent an MRI scan, this time, allowed to enter REM sleep.

Once the subjects became lucid, they signaled their awareness with a specific set of eye movements so researchers could take MRI pictures of brain activity. They then gave another set of eye signals to demonstrate that, in the dream, they were now alternating between clenching their hands.

Each time the dreamers indicated that they were clenching a hand, the scientists were able to take down timestamps. Of course, the participants weren’t physically moving their hands, but amazingly, the results of the MRI scans proved that they weren’t lying; the same regions of the brain that were active during the physical movements lit up when the lucid dreamers clenched in dreams. With these results, the scientists had gained objective proof that lucid dreamers can not only control when they are dreaming but can also control what it is they dream.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

One of the sponsors of the episode today is our good friends at the athletic clothing company, Vuori. They have a special deal for you all where you can get 20% off your purchase when you visit vuori.com/mattwalker. Vuori produces high quality clothing, and they offset their carbon footprint 100%, both of which, of course, mean a great deal to me. So, if you like athletic clothing, and you wish to help the planet out, then check them out at vuori.com/mattwalker. 

Another sponsor of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities important to maintaining your blood biochemical balance. So, if you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Today’s episode focuses on a second but very different function of dreaming: the ingenious processing and interconnection of memories that inspires creativity and even problem-solving ability.

Matt describes how we can think of REM sleep dreaming as a form of informational alchemy, in which we build new connections. As a consequence, we wake the next morning with a mind-wide web of associations capable of divining solutions to previously impenetrable problems.

A great illustration of dream-inspired creativity is the chemist Dmitri Mendeleev, who had been trying for years to solve arguably the greatest problem of his time: how do all of the elements in the universe fit together? When Mendeleev finally lay down to sleep, his dreaming brain came up with the Periodic Table. It’s not just in the sciences that we’ve seen dream-inspired insight. Consider, for example, Sir Paul McCartney’s origination of the songs “Yesterday” and “Let It Be,” both of which came to McCartney in his dreams. 

Matt and his team conducted a study which found that participants were 30% better at solving cognitive problems when they were woken up out of a REM sleep dreaming state. Moreover he found that the way you solve problems is different when you’re coming out of REM sleep dreaming. Matt suggests that this reflects the biological basis of creativity. Importantly, it’s not just that you dream, but once again, what you dream about that seems to matter.

Little wonder then we’re never told to, “stay awake on a problem.” Instead, we’re told to 'sleep on it'. That phrase, or something close to it, seems to exist in most languages that Matt has enquired about, indicating that the problem-solving benefit of dream sleep is universal.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth.

So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Matt’s back with part three of his series on the science of dreaming! In this episode, he discusses how he and other scientists have discovered that dreams are not simply an  unintended by-product of REM sleep. Instead, dreams provide at least two essential benefits for human beings.

The first of these functions involves nursing our emotional and mental health and is the focus of this episode. Matt helps us understand that what makes a memory emotional is that, at the time of the experience, we release a visceral, emotional reaction. This wraps itself around the memory and red flags that memory/experience as important, and tags and bonds itself to the information, creating an “emotional memory.” 

Years ago, Matt and his team discovered that it’s not time that heals all wounds. Instead, it is sleep, that helps the brain divorce the emotion from the memory, offering what Matt has described as, “a form of overnight therapy.” Dreaming of these emotional events allows mental-health resolution, keeping our minds safe from the clutches of anxiety and reactive depression.

Earlier work by pioneering researcher Dr. Rosalyn Cartwright addressed the latter condition of depression. Her remarkable work studied the dreams of people showing signs of clinical depression due to difficult emotional experiences. Through her research, Dr. Cartwright found that only those patients who had been dreaming about their painful experiences went on to gain clinical resolution from their depression. 

When it comes to resolving our emotional difficulties it’s not enough to have dreams. Instead, we seem to need to dream of the events themselves to benefit from that emotional therapy. 

Now if you’re not remembering dreams of difficult experiences you’ve been going through, don't worry. If Matt brought you into his sleep center and woke you while you were having REM sleep, your dream reports would most likely reflect that you are doing exactly what you need to be doing in terms of your emotional processing.

In other words, all of this work tells us that one of the functions of dreaming is to serve as a set of emotional windscreen wipers! As a result when we wake the next morning after a night of dreaming, we are dressed in a very different set of psychological clothing to that we went to sleep in--a less ruffled emotional outfit, free of the sharp creases of painful emotions.

What Matt and his team discovered is that it’s not time that heals all wounds, but rather, it is time spent in dream sleep that provides emotional convalescence. 

To sleep, perchance, to heal.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this particular episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

In the second episode of this series about REM sleep dreaming, Matt explores what the science has to say not only about how we dream at the brain level, but what it is that we dream about.  

Traditionally, civilizations such as those in ancient Egypt, believed that dreams were a form of divine intervention--a message from the heavens. Thereafter, Matt discusses Sigmund Freud, who introduced the notion of dreams originating from within the brain, not the heavens, and thus could be considered a science of the brain/mind. However, Freud went on to develop the (non-scientific) theory that dreams reflected the expression of our subconscious desires, but that those repressed wishes were transformed and disguised by the brain into a dream narrative.

Freud's theory suggests that, as we dream, our repressed wishes pass through a sensor in our mind, and then come out the other side as unrecognizable experiences to the dreamer.  Freud believed that he understood how the sensor worked and could decrypt the disguised dreams, and thus know something about his patients that he could share with them. Matt notes that Freud's theory could never be proven right, nor wrong, and also why we no longer consider it as a valid scientifically rigorous theory.

Next, Matt delves into modern-day scientific methods that have led to new theories of why we dream, including a theory that dreams are a replay of our waking life experience of our past memories. 

He recounts the work of his friend, Dr. Robert Stickgold, who found that only 1 to 2% of our dreams are really true clear replays of our prior waking life events. Matt also notes that, based on the same findings, there is a red thread narrative that runs from our waking lives into our dreaming lives = emotional concerns that we're having during the day, and the social individuals connected to those things.

Matt describes the latest research from a team in Japan that used MRI scans to predict the content of dreams. Matt postulates that science is getting ever closer to having the ability to know exactly what we are dreaming, and perhaps, take away ownership of the dream process from the dreamer itself.

Matt draws this episode to a close by asking some thought-provoking questions about whether we are truly responsible for what we dream about, and whether we should be held responsible for what we dream.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth.

So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

This week’s episode is the first in a new multi-part series all about dreams! Today, Matt focuses on the question of how your brain generates these things called dreams.

Matt starts with an unexpected statement: last night, when you were dreaming, you became psychotic. 5 things happen when you dream that justify his diagnosis: 1)  you see things that aren’t there, 2) you believe things that could not be true, 3) you become confused about time, place, and person, 4) you have wildly fluctuating emotions, and 5) you wake up in the morning and forget most of this dream experience, amnesia. If you experience any of these symptoms while awake, you might seek psychological attention. Yet,  dreaming is both a normal and, essential biological and psychological process.

Matt explains that REM sleep is not the only stage of sleep when we dream. However, the things that most of us call dreams, involving movement, emotions, past memories, and rich narrative, largely come from REM sleep. 

Over the past 20 years, a new scientific view of REM sleep has given rise to an understanding of 3 basic questions regarding dreaming. 1) how does the brain create this neural activity called dreaming? 2) can we explain if dreams have their source in our experiences, or are they de novo experiences generated by the brain? 3) what is the function of REM sleep dreaming? The advent of brain-imaging machines allowed scientists like Matt to create beautiful 3D visualizations of people’s brains as they dreamt.

When the brain switches from deep non-REM sleep over to REM sleep, something remarkable happens: the brain erupts with spikes of activity in the MRI scans. Specifically, 4 areas of the brain fire up when dreaming starts during REM sleep: the visuospatial regions, the motor cortex, the hippocampus, and the amygdala. In contrast to all of these areas, one part of the brain does the opposite. The left and right sides of your prefrontal cortex becomes markedly deactivated during REM sleep. This is important because your prefrontal cortex controls logical reasoning. This is, in part, why dreams are often filled with movement, strong emotions, past memories, people, and experiences, yet are utterly irrational. 

Finally, Matt reminds us of one last fact. When we are in REM sleep dreaming, the body is paralyzed, preventing us from acting out our bizarre dreams. Otherwise, we would put ourselves in danger and be popped out of the gene pool rather quickly!

Be sure to tune in for the rest of the series to uncover even more fascinating information about these things we call dreams.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering a special 31% off any one of their programs if you use the above link during the time window of this particular episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

Matt has a special announcement this week: a new recurring type of episode called, ‘Sleep is Bloody Remarkable’. This series of episodes will share fascinating facts about sleep that will  blow your mind! In the premier episode, Matt focuses on something truly (bloody) remarkable: half-brain sleep, or unihemispheric sleep.  

Unihemispheric sleep is the phenomenon of when one hemisphere of the brain is awake, while the other sleeps. Matt goes on to discuss how the two sides of the brain rotate their sleep roles, such that after a set period of time, the side that got to undergo sleep first wakes, so that the other half of the brain gets its needed opportunity for sleep.  

Whales and dolphins are great examples of half brain sleepers. They need to maintain movement in their underwater environment. Half-brain sleep allows them to still do this while still getting plenty of NREM slumber (just one half of the brain at a time).  Birds are also capable of half-brain sleep. Birds use unihemispheric sleep for survival purposes, although for different reasons. Birds use it to keep one eye on things, literally!  

When birds land as a flock, the birds on the farthest left and right sides - the sentinels, as it were - undergo unihemispheric sleep, to keep one eye open for threat detection on their respective side (180 degree views on the left and right). The result being, combined, the entire flock gets full 360 degree panoramic threat detection. Indeed, all of the rest of the birds are allowed to sleep with both hemispheres i.e., full brain sleep.

The poor birds on the sides don’t actually get the chance to come into the middle of the flock, it seems. Instead, to get equal sleep on both sides of the brain, when one hemisphere has fulfilled its sleep need, these birds will rotate 180 degrees, and switch sides of the brain that is sleeping. Bloody remarkable! 

We humans undergo our own rendition of unihemispheric sleep…sort of =)  In an unfamiliar location, such as a hotel room, humans keep one of their hemispheres on guard in this potentially dangerous context. Meaning, one half of the brain does not go into as deep NREM sleep, almost as if it is remaining semi-conscious. Matt also notes that half-brain sleep only happens during NREM sleep. When all species go into REM sleep, both sides of the brain sleep. There is no unihemispheric dream sleep, it seems. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth.

So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Matt returns with Part 2 of his series on sleep and weight gain. This time around, he teaches us how a lack of sleep not only makes you eat more food, but changes what types of food you want to eat, and eat to excess.

First, Matt describes how underslept individuals that are limited to 4-5 hours of sleep for several nights will experience a 33% increase in the desire to eat obesogenic, sugary treats. In addition, they will suffer a 30% increase in craving for heavy-hitting carbohydrates, like pasta and pizza, and a 45% increased desire for salty snacks!

Matt goes on to explain that your brain plays a role in this sleep loss-weight gain equation. In one of his experiments, a group of normal, healthy-weight individuals went through the study twice: once when sleep-deprived and once after a full night of sleep. After each condition, the individuals were placed inside an MRI scanner and shown different food types, and asked to rate how much they wanted each food item. 

What they found is that the sleep-deprived brain changed markedly, shifting to a pattern of activity associated with what is called hedonic eating, or impulsive eating. Specifically, the prefrontal cortex, which is responsible for impulse control, was shut down by lack of sleep. As a result, the very primitive deep brain regions that drive excessive appetite become hyperactive and hyper-responsive to highly desirable, unhealthy food items, such as ice cream and donuts, rather than nuts or leafy greens.

He also reveals that staying awake across the night doesn't burn vastly more calories. You only burn about an extra 140 calories by staying awake all night relative to being asleep, yet you will eat more than twice that amount more in calories when sleep-deprived. Plus, you are less active when sleep-deprived, so you don't burn off those calories. 

Worse still, Matt tells us that dieting becomes ineffective without sleep: 60% of the pounds you will lose come from lean body mass (such as muscle), and not fat.  Specifically, when you are sleep-deprived, the body becomes especially stingy with fat, stubbornly refusing to give it up. In other words, you end up losing what you want to keep, which is muscle, keep what you want to lose, which is fat. Also, inadequate sleep increases levels of cortisol, which also makes your body store food as fats.

Matt concludes with an optimistic note by highlighting the fact that getting enough sleep is a scientifically proven way to help you regulate your appetite and a healthy body composition (a little bit less painful than going to the gym!?)

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

In this episode, Matt delves into the curious and cautionary tale of Delta Sleep-Inducing Peptide (DSIP), once hailed as a potential miracle cure for insomnia. In the 1970s, researchers were on a quest for a single "somnogenic molecule" that could act as the brain's natural sleep switch. A Swiss team believed they had found it, isolating a peptide that appeared to rapidly induce deep, slow-wave sleep when injected into animals. This initial excitement led to bold claims and sparked decades of research into what seemed to be a revolutionary breakthrough in sleep science.

However, the promising discovery soon began to unravel under closer scientific scrutiny. Red flags emerged, including the inability to find the gene that coded for DSIP and the peptide's extreme fragility, which prevented it from effectively reaching the brain. When rigorous, placebo-controlled human trials were finally conducted, the results were profoundly disappointing, showing no significant clinical benefit over a placebo. Ultimately, the story of DSIP serves as a powerful lesson on the dangers of scientific overconfidence, the critical importance of replication and skepticism, and the profound complexity of sleep regulation, reminding us that there is no single "magic bullet" for a good night's sleep.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

In a supplement industry where trust is critical, Matt uses podcast partner Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

Matt kicks off a two-part series all about sleep, eating, and weight gain. 

He starts by introducing two appetite-regulating hormones: leptin and ghrelin. Matt explains how leptin sends a signal of fullness, to your brain. When leptin levels are high, your appetite is reduced, and you feel satisfied by the food you eat. Ghrelin does the exact opposite. It revs up your hunger, so when your ghrelin levels are high, you don’t feel satisfied by the food you ate, so you want to eat more.

Matt tells us that when you’re not getting enough sleep, the levels of these two hormones are affected in unfortunate ways, causing you to feel less full and more hungry. Specifically, sleep loss decreases leptin levels by 18%, yet increases ghrelin levels by 28%!

So when you are not getting enough sleep, the body losses the fullness signal AND suffers an increase in hunger levels. The combined consequences? Your appetite rockets up!

It’s also been discovered that levels of endocannabinoids --a class of cannabinoids we naturally produce ourselves -- increase sharply in response to a lack of sleep. As a result,  your hunger levels increase even more (as you may know, cannabinoids are part of the reasons that cannabis gives you the munchies).

Adding up all of these effects, Matt describes how this lack of sleep causes people to consistently overeat. Usually somewhere between 250 to 400 extra calories each and every day!

Snacking also becomes a problem. For example, if you present a group of people with a large meal of over 1,000 calories, then give them the option to keep snacking,  under-slept individuals will continue to snack, consuming an additional 200 to 300 calories relative to those who’ve been getting a full eight hours of sleep.

This all begs the question: is there a reason why your hunger goes into overdrive when you are under-slept? Matt explains one plausible theory from an evolutionary perspective, based on the fact that when animals are in a starvation state, the brain keeps them awake longer so they can forage further. Therefore, when the brain doesn’t get enough sleep, it thinks we may be in a state of starvation and increases our desire for food.

Finally, notes what's coming in part two:  that insufficient sleep not only increases how much you eat but changes your food preferences, and changes how your bodies deposit the extra calories we take on as our hunger increases, relevant to body fat accumulation.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order, 2) a one-year free supply of vitamin D, and 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth.

So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts you’d like to share, please reach out to Matt on

In the previous episode, Matt described the role of temperature in helping us fall asleep. In this episode, Matt teaches us all about the role of temperature in helping us stay asleep across the night, and then more effectively wake up the following morning.

First, Matt takes us back to the body temperature suit experiments that were able to warm or cool different parts of the body. Matt explains that, using this same method, when you continue to cool the body throughout the first and middle parts of the night, enhance the ability of individuals to stay asleep more soundly across the night, increase the amount of deep sleep, and boost the electrical quality of that deep sleep.

Matt explains why a warm bath or shower before bed helps you sleep, perhaps for the opposite reasons you think. It is not that you get warm and toasty ready for bed. Instead, when you get out of the bath or shower, all of the blood races to the surface of your skin. As a result, your core body temperature plummets, enabling you to fall asleep faster and stay asleep more easily.

Matt also discusses how external ambient room temperature impacts our sleep at night. He notes that the optimal temperature for sleep at night for the average adult is between 16-18 degrees Celsius, or 61-65 degrees Fahrenheit, although everyone will be a little bit different, of course.

Finally, Matt explores the effect of temperature on waking up. He notes that as you move into those late morning hours of sleep, particularly as you start to enter the REM sleep-rich phases of your sleep cycle later in the morning, your central brain temperature rises significantly. 

Indeed, it is in the last 30 minutes before people would naturally wake up in the morning that their body temperature starts to increase markedly. Matt goes on to describe how this increase in temperature is a signal that triggers the beginning of the awakening process.

Related to this, Matt notes that waking up can be challenging for many people, especially if you're not sleeping in synchrony with your chronotype. However, Matt suggests that one way you can facilitate the process of waking up more effectively is by trying to warm up the ambient temperature of the bedroom in the last 30 minutes before your alarm goes off. So if you have a smart thermostat, try to program it to increase the temperature to around 21 degrees Celsius or approximately 70 degrees Fahrenheit in the last 30 minutes before your alarm goes off.

The bottom line is that many of us don’t realize how important temperature is to falling asleep, staying asleep, and enjoying an enlivened awakening the next morning.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

In today's episode, Matt reveals how 1) your own temperature and, even more precisely, 2) the temperature of different parts of you, as well as 3) the temperature of your bedroom, can change how well or how poorly you sleep at night.

Matt describes the basic physiology of how your brain and body needed to drop their core temperature by about 1 degree Celsius, or about 2 to 3 degrees Fahrenheit, for a person to fall and stay asleep across the night. This is the reason why we will always find it easier to fall asleep in a room that's too cold than too hot because the room that's too cold is at least taking you in the right temperature direction for good sleep at night.

Matt teaches us that, ironically, one important way to drop your core body temperature is to warm up your extremities, specifically your hands and feet. He explains that it's one of the key ways your body regulates temperature. 

To drive his point home, Matt points to research showing that if you gently warmed the paws of rats, it encourages the blood to rise to the surface of the skin of those paws, away from the core of the body.  By emitting heat away from the body's center, it drops core body temperature rapidly, and as a result, the rats drifted off to sleep far faster than was otherwise normal.

Matt complements all this with a study in humans using a whole-body temperature sleeping suit, a little like wetsuit, but with tubes throughout that can warm or cool different parts of the body with warm or cool water.  

In the first series of studies, researchers selectively warmed the feet and the hands by just a small amount, which caused a rising of the blood to the surface of the skin. As they warmed the body's extremities, the core temperature of the participants dropped, and the upshot was that these healthy individuals were falling asleep 20% faster than was normal.

In the second round of studies, even more remarkable, if you manipulate the temperature in this way in older adults, they will fall asleep 18% faster than typical, and insomnia patients will fall asleep a full 25% faster than usual with this same method. 

The impact of temperature on sleep is therefore clearly significant, but there is even more to this thermal story, including how you can best wake up from sleep feeling alert, which is what Matt will discuss next episode. 

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram.

In today's episode, Matt takes us on a deep dive into melatonin. He covers four main topics: 1) what is melatonin? 2) how does melatonin work? 3) what does melatonin do, and *not* do, for sleep? 4) how can we think about melatonin supplementation?

First, Matt describes that melatonin is a naturally occurring hormone released by the brain. He gleefully notes that melatonin is often called, “the vampire hormone” as it comes out at night. In doing so, it signals that it is nighttime, which in turn helps schedule sleep.

Second, Matt explains that, during the day, light enters your eyes, and inhibits the release of melatonin. This absence tells your brain that it's daytime and time to be awake. Fast-forward to the evening, and the arrival of darkness, the floodgates of melatonin release open up. We need darkness in the evening to trigger this release, and, in turn, tell your brain that it's nighttime and time to sleep.

Matt highlights one significant problem of the present age: we live in a dark-deprived society. Many of us get too much artificial light, and not enough darkness. He shares a tip to dim down half of the lights an hour before bed and avoid screens.

Third, Matt elaborates on what melatonin does and does not do; that is, melatonin helps schedule the *timing* of your sleep but does not significantly change the *quality* of sleep. He uses the analogy of a race, where melatonin would be the official who begins the great sleep race but does not participate in the race itself.

Finally, Matt discusses supplementation. You can buy melatonin in certain countries to try to use it as a sleep aid. Based on scientific data across the past 15 years, Matt notes that melatonin isn't as effective as you may think: a recent meta-analysis discovered that melatonin only increases the speed with which you fall asleep by 3.9 minutes, and only improves your sleep efficiency by just 2.2%. This reinforces his point that the role of melatonin is primarily in regulating the timing of your sleep, not in sleep generation. 

Matt states that melatonin is not well regulated as a supplement, and that the strength of melatonin that you buy is often unreliable. He describes a study that examined over 15 different suppliers. Strikingly, when tested, the concentration of melatonin within each pill ranged from 83% less to 478% more than what was stated.

Finally, Matt advises that the best way to optimize your sleep is to rely less on melatonin supplementation, and instead, focus on the basics we know make a real difference: sleep regularity, keeping your bedroom cool, getting darkness in the evening, get plenty of natural daylight during the morning, do some physical activity each day, and perhaps most importantly, address your stress and anxiety.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice, nor prescriptive in any way.

The sponsors of this week's episode are InsideTracker. They are offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

In this week’s episode, Matt continues his discussion of sleep and caffeine. Here, we learn about the paradox of coffee, one in which coffee provides health benefits, despite its negative impact on sleep.

Before addressing that, however, Matt speaks about one last sleep consequence of caffeine: regardless of your sensitivity to caffeine, it can still disrupt the quantity and electric quality of your deep non-REM sleep.

This can lead to a cycle of caffeine dependency 1) you drink more coffee the next morning to compensate for your poor-quality, unrestorative sleep the night before, which then 2) degrades the quality of your subsequently night's sleep even more, which leads to 3) your potentially reaching for even more sups of coffee the following day, etc, etc.

Matt’s advice to still drink coffee (if you want) is due to the many health benefits associated with coffee. How is it possible that coffee has such health benefits, despite the harmful impact of caffeine on sleep?

Matt points out that the coffee bean itself contains a sizable blast of antioxidants in every cup. In fact, because of the state of the standard Western diet, coffee is the biggest source of antioxidants for many people in developed nations. However, it is possible to get these benefits without drinking caffeine – many health benefits are similarly associated with drinking decaffeinated coffee since that too contains antioxidants.

Therefore, it is the antioxidants in the coffee bean, not the caffeine, that carries the health-related advantages.

But Matt is also clear to speak about the fact that when it comes to coffee, the dose, and the timing make the poison. His advice: try to limit it to one to three (at the max) cups in the morning, remembering the quarter-life of caffeine is around 10-12 hours for the average adult. 

By following these steps, you can maintain a healthy relationship between caffeine, coffee, and this beautiful thing we call sleep at night.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The episode is sponsored by the incredible folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

In today's episode, Matt unpacks the world of coffee, and caffeine in the first of a two-part series on caffeine. Matt describes the numerous health benefits associated with coffee, the fact that Matt has even changed his tune a little and advocates a morning cup for some. Matt may not have anything to do with caffeine itself, with more details on that in part 2. In part 1, Matt then takes a deep dive into the different ways in which caffeine negatively impacts your sleep, some of which you may be less familiar with.

The first is that caffeine makes it harder for you to fall asleep. Due to activation of the nervous system, caffeine can lead to that unpleasant experience of a racing mind that won't shut off in bed—almost a Rolodex of anxiety that leads to ruminating and therefore catastrophizing.

The second impact is that caffeine makes it more difficult for you to stay asleep soundly across the night. This is due, in part, to the fact that caffeine makes your sleep more unstable and fragile, so  up more frequently at night. The consequence is something that scientists and doctors call sleep fragmentation, meaning that your overall sleep efficiency, or the consistent quality of your sleep, becomes significantly worse when you have caffeine on board.

The third feature that Matt points out centers on caffeine’s duration of action. Caffeine has a half-life of between five to six hours in the average adult. This means that, after five to six hours, 50% of that caffeine is still in your system. What this also means is that caffeine has a quarter-life of approximately 10 to 12 hours for a typical adult. 

Here, Matt gives us some context: if you have a cup of coffee at 2 PM, a quarter or more of that caffeine could still be circulating in your brain at midnight. Meaning, if you have a cup of coffee at 2 PM, it may be the equivalent of getting into bed at midnight, and just before you turn the lights out, you swig a quarter of a cup of coffee and you hope for a good night of sleep.

Matt, however, points out that the 10 to 12 hours quarter-life of caffeine is for the average adult, but this varies significantly from one person to the next. He explains in detail why this is the case: based on differences in genetics, different people will have a more or less efficient version of an enzyme that clears caffeine from their system. Some people will have a version of that enzyme that allows them to remove the caffeine from their system very quickly, whereas other people will have a version of the enzyme that is much slower in its speed of clearing caffeine.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.The good people at InsideTracker are the sponsors of this week’s episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

On last week’s episode, we learned about the three main ways alcohol can harm our sleep: 1) alcohol results in sedation rather than naturalistic sleep, 2) alcohol causes sleep fragmentation, and 3) alcohol impairs REM sleep. 

Today, Matt dives into each of these negative impacts, explaining exactly how and why alcohol disrupts our sleep in these specific ways.

First, alcohol is a class of chemicals called “the sedatives,” and sedation is not natural sleep. Healthy sleep is a very active, highly coordinated event within the brain, unlike sedation. As a result, alcohol can result in you waking up and feeling unrestored and unrefreshed by that non-normal sleep. 

Second, we normally need to shut off our fight-or-flight branch of the nervous system, called the sympathetic nervous system, and shift over to the calming, parasympathetic nervous system, in order to stay asleep soundly across the night. However, alcohol reactivates the fight-or-flight nervous system, forcing the brain and body back into a more hyper-alert state. 

This increases the chances of you waking up and staying awake, causing your sleep to become more fragile and prone to fragmented awakenings throughout the night. Alcohol also triggers the release of several stress-related chemicals, including cortisol. This stimulates the fight-or-flight nervous system and emotional centers in the brain, also making it more likely that you will wake up and stay awake.

Finally, alcohol significantly reduces the amount of REM sleep the brain can produce. Specifically, the metabolic byproducts of alcohol degradation within the body disrupts and impairs the generation of REM sleep. Without that REM sleep, we can suffer impairments to our cognitive brain function and emotional stability. We can also experience a heightened amount of negative moods, such as anxiety. REM sleep is also the time when we hit our peak in the release of important hormones, like testosterone, which is critical for both men and women.

While Matt acknowledges that this news may not be especially encouraging or popular, he closes out today’s show with a reminder that life is to be lived. It is not his intention to tell anyone how to live their life. Instead, Matt’s goal is to simply lay out the scientific evidence regarding the relationship between sleep and alcohol, so that you can make an informed decision about how to best structure your own sleep schedule and find an enjoyable life balance.

Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as medical advice in any way, shape or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

Although some people may believe that a drink or two in the evening will help them sleep better, today’s episode shows us that alcohol harms our sleep in several different ways. In the first of two episodes on sleep and alcohol, Matt talks about alcohol as a chemical, and the main ways it negatively affects our sleep.

Alcohol has a sedative effect that switches off brain cell firing as we sleep. Alcohol also fragments our sleep, making it less restorative, and blocks REM sleep, which is critical for numerous aspects of health and wellness, including learning and memory, creativity, rebalancing moods and emotions, recalibrating certain hormone systems, and even lifespan longevity.

Matt describes the clock-counter system our brains use to track lost REM sleep, and why we sometimes experience strong, intense and vivid dreams in the late hours of our sleep after too much alcohol as a result. 

In today’s episode, you’ll also learn about the specific ways in which alcohol interferes with our sleep quality, and the different stages of our sleep, REM sleep especially. 

Be sure to tune in next week as Matt further examines exactly what it is about alcohol that disrupts our sleep in these particular ways, and what the consequences are on health and wellness.

Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as medical advice in any way, shape or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

As the great Roman poet, Ovid, once said, “There is more refreshment and stimulation in a nap, even of the briefest, than all the alcohol ever distilled.” But are naps always a good thing? Are we even designed to nap? And if you do nap, when should you do it, and for how long? 

Today Matt explores the benefits and pitfalls of napping, how napping may fall in line with our pre-programmed sleep patterns as humans (a natural drop in alertness between 1 and 4pm each day), and what it means if you find yourself waking up from an accidental nap on the couch right before bed. 

You’ll also hear about the NASA nap culture, sleep inertia (which can include a feeling of a “sleep hangover”), and Matt’s advice for how to use naps to your advantage. If done correctly, for most people not struggling with sleep or insomnia, naps can improve alertness, task performance, creativity, and even reduce blood pressure. However, there is a dark side to napping that Matt discusses in detail, and why that can be the case. So join Matt as he walks you through both the advantages and disadvantages of napping!

Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as medical advice in any way, shape or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

Detailed Scientific Literature

Naps and overview (by the amazing Prof. Christopher Barnes)

The good and the bad of naps

Naps and Mortality

Naps, Brain function & Performance

​​

In the final episode of our three-part series about chronotypes, Matt examines the question of  whether your chronotype is truly fixed, or if you can change an evening type to a morning type (though you will hear that Matt’s preference is for society to change, not the individual). 

Matt reviews a fascinating study by an Australian-lead research team that tried to turn night owls into morning larks. Participants had to follow a series of strict rules over the course of a three-week study. This included things such as: setting an alarm to wake up two to three hours earlier than their normal wake time, eating breakfast first thing after waking up, getting outside for as much natural daylight as possible, and not having any caffeine after 3pm. 

As you’ll hear from Matt, the experiment was...somewhat successful. By the end of the study, evening types went to bed about two hours earlier than usual, managing to get to be around 12:30am, instead of 2:30am. In addition, their performance on several standardized cognitive tasks also improved expressly during the morning hours, when night owls typically struggle the most. 

However, as Matt points out, participants were still opting to go to bed after midnight, which is far from morning night-owl-like, and far from being turned into a morning type. It is also unlikely these individuals could continue with this rigid new set of experimental guidelines across the long-term, for their entire lifespans.

In other words, the results are fascinating, but the practice itself may not be sustainable in the real world. Instead, Matt's wish is that we simply allow evening types to sleep in harmony with their genetic chronotype. If night owls were able to sleep and wake up when they are biologically designed to, the world would be a happier, healthier place indeed.

Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as medical advice in any way, shape, or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

Basic Resources 

Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)

Scientific Review: Biological Rhythm and Chronotype

Matt explores the human capacity for echolocation this week, dismantling the myth that this "biological sonar" is exclusive to animals. Revealing how peer-reviewed research shows all human brains possess the neural hardware to "see" with sound, Matt explains the physics of how sound creates detailed acoustic maps of our environment and introduces the brain's remarkable plasticity, setting the stage for this incredible sensory adaptation.

The episode features stories of pioneers like Daniel Kish, who use echolocation to navigate with astonishing precision. Matt discusses groundbreaking studies from UC Berkeley and Durham University, where brain scans revealed the visual cortex rewires itself to process sound as spatial information. This evidence proves echolocation is not a rare gift but a learnable skill, forcing a reevaluation of the limits of human perception and the brain's adaptive power.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.

Another partner, AG1, is one that Matt relies upon for his foundational nutrition. Their new science-backed Next Gen formula features upgraded probiotics, vitamins, and minerals. Start your subscription today to get a FREE bottle of Vitamin D3+K2 and 5 free travel packs with your first order at drinkag1.com/mattwalker.

In a supplement industry where trust is critical, Matt uses podcast partner Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat, 

YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

In the second episode of our three-part series on chronotypes,  Matt speaks about what happens when you do not sleep in harmony with your natural chronotype. Unlike morning larks, night owls simply cannot fall asleep easily early at night, which leads to the first and most obvious consequence of not sleeping in line with your chronotype—you don’t sleep as much.

Matt explains that morning types sleep over 7-hours per night on average, while evening types can only manage 6.6-hours of sleep per night. Matt also notes the upshot, which is a chronic “sleep debt”, one that accrues night after night, month after month. The ramifications are many, including increased caffeine intake for evening types, higher likelihood of developing hypertension and Type II Diabetes, and greater difficulty maintaining a healthy body weight. In addition to these consequences to the body, evening types are two to three times more likely to develop depression than their morning type counterparts, and twice as likely to be using antidepressants. 

Matt clarifies that his intent in sharing the concerning statistics is not to worry evening types, but rather, to help them realize their true biological nature, and as important, not feel guilty for it. Today’s episode aims to vindicate and empower evening types with the knowledge that they may be sleep deprived, and to help them find a schedule that falls in line with their natural chronotype.

Matt Finally speaks about current societal practices that push (actually, force) night owls into unhealthy sleep rhythms. He outlines his (lofty 😊) goal of restructuring the typical schedule of work in first-world nations, which is strongly biased toward early start times that incorrectly punish night owls and favor morning larks. Matt notes that this is markedly unfair, since it is not their choice as to which ‘type’ they are. Instead, it is their pre-ordained, genetic-based sleep chronotype, yet society wrongly assumes that evening types could get up earlier if only they weren’t so slovenly. Of course, the science and this episode tells us otherwise.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

Basic Resources 

Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)

Scientific Review: Biological Rhythm and Chronotype

Scientific Review: Chronotype and Mental Health: Recent Advances

Episode 04: Chronotype: Part 1

Summary

Are you a morning type? Or are you an evening type? Perhaps you are neither of the two? Today’s episode is the first in a three-part series all about your chronotype, or your body’s natural biological preference to be awake and be asleep at a certain time. 

Matt begins by explaining exactly what your chronotype is, then breaks down the three main “flavors” of chronotype (morning lark, night owl, or somewhere in-between). In addition, and listed in the show notes, below, he explains how to determine whether you are a night owl or a morning lark. 

He will also describe how an individual’s sex falls into the equation and the difference between your chronotype and your circadian rhythm. 

You’ll hear about the key ways in which evening types biologically differ from morning types, that your chronotype isn’t your own choice nor is it your own fault, but rather, there is a very strong genetic basis of why and how you are programmed in terms of being a morning or an evening type? 

Today’s main takeaway is that when you or when society tries to force you to sleep in opposition to your biology, there can be unfortunate consequences. Stay tuned as we explore these in greater detail next time.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic. 

So, head on over to Athletic Greens www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram @drmattwalker.

Basic Resources 

Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)

Scientific Review: Biological Rhythm and Chronotype

Scientific Review: Chronotype and Mental Health: Recent Advances

#03 Circadian Rhythms

Continuing on from last week’s episode about sleep pressure, today, Matt Walker dives into the second half of the sleep-wake story, circadian rhythm. 

Matt explains that your circadian rhythm, or your 24-hour internal clock, begins drumming out its loud activating beat just before you wake in the morning and gets louder throughout the day, peaking in the early afternoon and hitting its lowest point in the middle of your sleep phase overnight. 

Matt describes how circadian rhythm and sleep pressure work independently of one another, yet coincide with a beautiful synchronicity to naturally and gently rouse you from sleep in the morning and rouse you into full wakefulness, then pull you into a wonderful, restorative sleep at night. 

You’ll also hear about the reliable mid-afternoon drop in alertness we see each day, what this means in terms of how humans were designed to sleep, and why it may explain the occasional need for a siesta.

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The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to  www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today.

Finally, if you have thoughts on sleep topics that you want Matt to cover, or you have feedback you’d like to share so he can be better at podcasting, please reach out to Matt on Instagram @drmattwalker. He'd love to hear from you🤗!