In the CHRONO:MEDICINE podcast (formerly known as 247Muscle), your host (Dr. Jan-Frieder Harmsen) interviews scientists in the field of chronobiology, circadian rhythm, skeletal muscle physiology, exercise performance and sleep. The podcast aims to provide translational knowledge from research findings for students, researchers and the generally interested public.
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E28 - The Central Clock & Melatonin with Michael Hastings (EBRS 2025 Spotlight 1)
Saison 2025 · Épisode 3
mardi 25 mars 2025 • Durée 01:14:44
In collaboration with the organizers of the 18th Congress of the European Biological Rhythms Society (EBRS) (taking place in Lübeck in Northern Germany from the 24th to 28th of August 2025), three congress speakers are interviewed to talk about their research. As the first spotlight, Prof. Michael Hastings (MRC Laboratory of Molecular Biology, Cambridge) talks about his research journey from circatidal rhythms in marine organisms to circadian and circaannual rhythms in mammals. Our main focus is on the neurochemistry within the central clock of the suprachiasmatic nucleus (SCN) enabling it to tell time. We discuss the most relevant factors that support the SCN in telling time, and what means the SCN has to synchronize other clocks within our body. With respect to melatonin, we discuss its role in sleep versus informing our body about the current season. We also talk about supplementing melatonin for specific populations. Lastly, Michael shares memories from attending previous EBRS congresses and why you should consider joining it this year.
Martha Gillette and others applied melatonin to brain slides containing the SCN, showing that this could shift the SCN clock, the sensitivity of the SCN to this melatonin effect was found to occur during daytime (when melatonin is not released naturally)
E27 - Part 2: A good night's sleep with Christian Benedict
Saison 2025 · Épisode 2
dimanche 16 mars 2025 • Durée 55:54
In this second part, Dr. Christian Benedict (Department of Pharmaceutical Biosciences, Research and Pharmacology at Uppsala University, Sweden) explains how our sleep changes with aging and upon different challenges of adult life. We discuss the so-called gold-standard method for measuring sleep (Polysomnography, PSG) and how modern wearable technologies perform compared to PSG. In this context, Christian evaluates the potential value of measuring heart rate variability (HRV) to assess sleep quality. He also emphasizes the health threat through obstructive sleep apnea (OSA) and how to use simple self-monitoring technologies to determine if you may be affected by OSA yourself. Lastly, we acknowledge poor sleep as a general health risk but also discuss limitations and problems that can arise from overstating this.
Chapters:
(0:00:12) Intro
(0:02:20) Aging and sleep
(0:11:10) Polysomnography (PSG)
(0:22:25) Sleep wearables & HRV
(0:27:07) Obstructive sleep apnea
(0:33:10) Limitations of wearables
(0:36:41) Sleep across chronotypes
(0:44:50) Poor sleep as a health risk?
(0:55:19) Outro
Studies that Christian refers to:
Meta-analysis (2004) PSG data over the lifespan
https://pubmed.ncbi.nlm.nih.gov/15586779/
Paper on app findings of almost a million people asked on “how long do you sleep?”
https://pubmed.ncbi.nlm.nih.gov/36509747/
Studies on PSG vs. some commercial wearables ?
E18 - Part 2: Daylight vs. electric light for health with Russell Foster
Saison 2 · Épisode 9
lundi 13 novembre 2023 • Durée 01:01:44
In the second part with Prof. Russell Foster (Head of the Nuffield Laboratory of Ophthalmology, and Director of the Sleep and Circadian Neuroscience Institute at the University of Oxford), contributing to the Daylight Awareness Week (13-17th of November 2023), we continue our discussion around the differential impact of daylight and electric light on health. We provide a historical perspective about human inventions that aimed to end the dependency on daylight - from fire to electric lighting. Prof. Foster further shares practical recommendations on how daylight and electric light can support health and well-being. Lastly, he gives an outlook on where the research around lighting and health is heading to in the future.
(0:27:18) Practical recommendations for evening lighting
(0:30:37) Architectural dilemma with daylight
(0:33:12) Early birds vs. Night owls
(0:37:35) Jet lag
(0:40:10) Drug development for blind people
(0:42:11) Mimick seasonal changes in daylight
(0:45:29) Russell’s personal outlook
(0:55:02) Funny anecdotes
E17 - Part 1: Daylight vs. electric light for health with Russell Foster
Saison 2 · Épisode 8
lundi 13 novembre 2023 • Durée 55:17
As part of the Daylight Awareness Week (13-17th of November 2023), Prof. Russell Foster (Head of the Nuffield Laboratory of Ophthalmology, and Director of the Sleep and Circadian Neuroscience Institute at the University of Oxford) talks about the differential impact of daylight and electric light on health. In the first part, we cover the basics of how daylight has shaped life on Earth and how it changes over the course of a 24-hour day. Prof. Foster further explains how light sets our inner time, the so-called circadian clock, and how light can influence sleep, alertness, cognitive performance, cardiovascular and metabolic health.
(0:26:02) Discovery of how light sets the circadian clock
(0:37:01) Central & peripheral clocks
(0:41:00) Melatonin is the darkness hormone
(0:48:05) Physiological modulation by light
(0:53:05) Outro & Teaser to Part 2
Russell Foster's recently published book: "Lifetime"
Papers/books that Russell refers to:
"Spectral Sensitivity Tuning in the Deep-Sea" (Douglas et al. 2003)
E16 - Part 2: Pre-sleep protein after exercise with Jorn Trommelen
Saison 2 · Épisode 7
lundi 10 juillet 2023 • Durée 50:37
In the second part with Dr. Jorn Trommelen (Assistant Professor, Department of Human Biology, Maastricht University, The Netherlands), we talk about Jorn's recent study on pre-sleep protein ingestion after acute endurance exercise to stimulate muscle protein synthesis. Jorn explains how these findings from acute studies relate to boosting long-term gains in strength, hypertrophy and endurance performance in response to regular pre-sleep protein ingestion. Based on his studies, Jorn shares his view on practical recommendations for pre-sleep protein in endurance- and resistance-training types of sports.
Main paper that we discuss in depth:
Pre‐sleep Protein Ingestion Increases Mitochondrial Protein Synthesis Rates During Overnight Recovery from Endurance Exercise: A Randomized Controlled Trial (Trommelen et al. 2023)
Long-term study on pre-sleep protein for muscle gains:
Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men (Snijders et al. 2015)
E15 - Part 1: Pre-sleep protein after exercise with Jorn Trommelen
Saison 2 · Épisode 6
mardi 27 juin 2023 • Durée 47:54
Dr. Jorn Trommelen (Assistant Professor, Department of Human Biology, Maastricht University, The Netherlands) talks about his research on pre-sleep protein ingestion after exercise to stimulate muscle protein synthesis. In the first part, we discuss the different forms of proteins and how endurance vs. resistance training differ in their post-exercise protein demand. Jorn further explains why the sleeping period is actually not so different from the awake period with respect to protein needs. We also dive into the details of the main methodological approaches used in Jorn's group to assess muscle protein synthesis.
Main paper:
Pre‐sleep Protein Ingestion Increases Mitochondrial Protein Synthesis Rates During Overnight Recovery from Endurance Exercise: A Randomized Controlled Trial (Trommelen et al. 2023)
Production of large amounts of [13C]leucine-enriched milk proteins by lactating cows (Boirie et al. 1995)
https://pubmed.ncbi.nlm.nih.gov/7815181/
First paper applying the model:
Slow and fast dietary proteins differently modulate postprandial protein accretion (Boirie et al. 1997)
https://pubmed.ncbi.nlm.nih.gov/9405716/
Paper from Jorn's group applying the model:
Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial (Weijzen et al. 2022)
E14 - Part 2: Health risks of shift work & how to minimize them with Frank Scheer
Saison 2 · Épisode 5
dimanche 21 mai 2023 • Durée 48:49
In the second part with Prof. Frank Scheer (Division of Sleep and Circadian Disorders, Brigham and Women's Hospital at Harvard Medical School, USA), we discuss what a night-shift worker could consider doing acutely (preceding, during, and following a shift) and chronically (when working years of shift schedules) to minimize health risks. In this context, we consider concepts like "sleep banking", when to exercise, caffeine ingestion, what to eat, light exposure strategies & more. We highlight which practical tools are supported by scientific evidence, whereas others seem promising but require further investigation. Lastly, Frank shares his view on how this research field around the health risks of shift work could in the long run achieve guideline changes for shift workers and how labor sectors that are dependent on shift work could be stimulated to improve working conditions.
Literature underlying practical recommendations:
Banking Sleep: Realization of Benefits During Subsequent Sleep Restriction and Recovery (Rupp et al. 2020)
Interplay of Dinner Timing and MTNR1B Type 2 Diabetes Risk Variant on Glucose Tolerance and Insulin Secretion: A Randomized Crossover Trial (Garaulet et al. 2022)
https://doi.org/10.2337/dc21-1314
Effects of caffeine on human behavior (Smith 2022)
https://doi.org/10.1016/S0278-6915(02)00096-0
Blue-blockers reduce melatonin suppression:
Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers (van der Lely et al. 2014)
E13 - Part 1: Health risks of shift work & how to minimize them with Frank Scheer
Saison 2 · Épisode 4
mardi 2 mai 2023 • Durée 59:25
Prof. Frank Scheer (Division of Sleep and Circadian Disorders, Brigham and Women's Hospital at Harvard Medical School, USA) introduces us to the topic of shift work and its adverse effects on many health aspects. We define the different forms of shift work with a particular focus on night shifts by painting a picture of what the everyday life of a typical nurse in the hospital looks like, and how working night shift possibly affects her health acutely and in the long term. Thereby, we cover the diverse side-effects of shift work on our physiology and cardiometabolic system as well as associated pathologies. After this general overview, we dive into two recent clinical studies performed by Frank Scheer’s group which focus on the question at what times a shift worker could eat or fast to lower the health burden.
Correction by Frank Scheer:
"The Medical Chronobiology Program was already founded in 2005, not 2015."
Main papers that we discuss in depth:
Daytime eating prevents internal circadian misalignment and glucose intolerance in night work (Chellappa et al. 2021)
Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity (Vujovic et al. 2022)
Adaptation of the circadian rhythm of 6-sulphatoxymelatonin to a shift schedule of seven nights followed by seven days in offshore oil installation workers (Gibbs et al. 2002)
https://doi.org/10.1016/S0304-3940(02)00247-1
E12 - Impact of cold vs. heat on exercise recovery with Cas Fuchs
Saison 2 · Épisode 3
mercredi 15 février 2023 • Durée 01:07:58
Dr. Cas Fuchs (Department of Human Biology, Maastricht University, The Netherlands) talks about two of his studies in which he separately investigated the effect of cold- versus hot-water immersion after exercise on recovery. In this context, Cas explains the acute physiological response to cooling and heating. We question what athletes claim or hope to achieve by applying cooling and heating strategies in practice and whether there is scientific evidence behind these claims. The primary focus of Cas' studies is how cooling and heating influence muscle protein synthesis after resistance training and he describes how muscle protein synthesis is measured in his research group. Based on his studies, Cas shares his practical recommendations on who might want to incorporate cooling or heating into his/her exercise routine with specific goals in mind.
Main papers that we discuss:
Postexercise cooling impairs muscle protein synthesis rates in recreational athletes (Fuchs et al. 2019)
Hot-water immersion does not increase postprandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males (Fuchs et al. 2021) https://journals.physiology.org/doi/full/10.1152/japplphysiol.00836.2019
Additional papers that Cas and I refer to:
Review on the muscle protein synthesis approach:
The Muscle Protein Synthetic Response to Meal Ingestion Following Resistance-Type Exercise (Trommelen et al. 2019)
Studies on lowering pain after exercise through the cold:
E11 - When to eat most of your calories with Alex Johnstone
Saison 2 · Épisode 2
lundi 13 février 2023 • Durée 01:13:55
Prof. Alexandra Johnstone (The Rowett Institute, University of Aberdeen, Scotland) talks about her recent study on the timing of calorie loading and its differential effects on weight loss and appetite control. Alex thereby investigated mechanisms behind the diet concept of "eating breakfast like a king". We further discuss the real-world implications of her findings and practical considerations for when to eat most of your calories for different populations.
Main paper that we discuss:
Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity (Ruddick-Collins et al. 2022)
https://www.cell.com/cell-metabolism/fulltext/S1550-4131(22)00344-8
Additional papers that Alex and I refer to:
Timing of food intake predicts weight loss effectiveness (Garaulet et al. 2013)
https://www.nature.com/articles/ijo2012229
High Caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women (Jakubowicz et al. 2013)
"Phototransduction by Retinal Ganglion Cells That Set the Circadian Clock" (Berson et al. 2002)
https://doi.org/10.1126/science.1067262
Russell's group to demonstrate the existence of retinal ganglion cells in mice:
"Melanopsin retinal ganglion cells and the maintenance of circadian and pupillary responses to light in aged rodless/coneless (rd/rd cl) mice" (Semo et al. 2003)
https://doi.org/10.1046/j.1460-9568.2003.02616.x
Retinal ganglion cells in the macaque:
"Melanopsin-expressing ganglion cells in primate retina signal colour and irradiance and project to the LGN" (Dacey et al. 2005)
https://www.nature.com/articles/nature03387
Skin of frogs, melanophores --> melanopsin
"Melanopsin: An opsin in melanophores, brain, and eye" (Provencio et al. 1998)
https://pubmed.ncbi.nlm.nih.gov/9419377/
VA opsin only in fish, not in mammals
"A novel and ancient vertebrate opsin" (Soni & Foster 1998)
https://doi.org/10.1016/S0014-5793(97)00287-1
Samer Hattar’s work: projections to the hypothalamus from melanopsin
"Central projections of melanopsin-expressing retinal ganglion cells in the mouse" (Hattar et al. 2006)
https://doi.org/10.1002/cne.20970
"Circadian photoreception in the retinally degenerate mouse (rd/rd)" (Foster et al. 1991)
Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects (Trommelen et al. 2021)
https://pubmed.ncbi.nlm.nih.gov/33487181/
Literature for peak times in myofibrillar vs. mitochondrial protein synthesis after exercise:
"Whereas myofibrillar protein synthesis rates are typically highest during acute post-exercise recovery (0–6 h) [28, 29], mitochondrial protein synthesis rates appear to peak at ~ 24 h of post-exercise recovery [25, 27, 30]. Therefore, it could be speculated that post-exercise protein ingestion may prove to be more effective at stimulating mitochondrial protein synthesis rates when assessed over a more prolonged recovery period [31]."
!See numbered references in the main paper stated above!
Generally 20g of protein maximally stimulates muscle protein synthesis:
Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men (Moore et al. 2009)
https://pubmed.ncbi.nlm.nih.gov/19056590/
Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise (Witard et al. 2014)
https://pubmed.ncbi.nlm.nih.gov/24257722/
Presleep dietary protein-derived amino acids are incorporated in myofibrillar protein during postexercise overnight recovery (Trommelen et al. 2018)
https://pubmed.ncbi.nlm.nih.gov/28536184/
Studies of protein’s impact on sleep
Protein intake and its effect on sleep outcomes: a systematic review and meta-analysis of randomized controlled trials (Wirth et al. 2023) https://academic.oup.com/nutritionreviews/article/81/3/333/6694939?login=true
Protein Ingestion before Sleep Increases Overnight Muscle Protein Synthesis Rates in Healthy Older Men: A Randomized Controlled Trial (Kouwe et al. 2017)
Circadian Photoentrainment in Mice and Humans (Foster et al. 2020)
https://www.mdpi.com/2079-7737/9/7/180
Exercise mitigates sleep-loss-induced changes in glucose tolerance, mitochondrial function, sarcoplasmic protein synthesis, and diurnal rhythms (Saner et al. 2021)
https://doi.org/10.1016/j.molmet.2020.101110
Prior Exercise Lowers Blood Pressure During Simulated Night-Work With Different Meal Schedules (Fullick et al. 2009)
https://pubmed.ncbi.nlm.nih.gov/19556971/
Impact of the human circadian system, exercise, and their interaction on cardiovascular function (Scheer et al. 2010)
Timing of Moderate-to-Vigorous Physical Activity Is Associated with Improvements in Glycemic Control in Type 2 Diabetes in the Look AHEAD Study (Qian et al. 2022)
https://doi.org/10.2337/db22-537-P
Heart attacks are more common in the morning:
Circadian Variation of Ambulatory Myocardial Ischemia: Triggering by Daily Activities and Evidence for an Endogenous Circadian Component (Krantz et al. 1996)
Shift Work or Food Intake during the Rest Phase Promotes Metabolic Disruption and Desynchrony of Liver Genes in Male Rats (Salgado-Delgado et al. 2013)
https://doi.org/10.1371/journal.pone.0060052
Timing of food intake predicts weight loss effectiveness (Garaulet et al. 2013)
Postexercise cold water immersion benefits are not greater than the placebo effect (Broatch et al. 2014)
https://pubmed.ncbi.nlm.nih.gov/24674975/
More long-term studies on cold water immersion on muscle mass and strength being lower (group from Australia):
Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training (Roberts et al. 2015)
https://pubmed.ncbi.nlm.nih.gov/26174323/
Previous study on muscle inflammation markers after cooling, but found no differences:
The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise (Peake et al. 2016)
Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity (Vujovic et al. 2022)
https://doi.org/10.1016/j.cmet.2022.09.007
Impact of Meal Timing and Chronotype on Food Reward and Appetite Control in Young Adults (Beaulieu et al. 2020)
https://www.mdpi.com/2072-6643/12/5/1506
James Bett's definition of breakfast is “within 2-3hours after waking”:
Is breakfast the most important meal of the day? (Betts et al. 2016)
Human circadian rhythms: a multioscillatory system. (Aschoff & Wever 1976)
https://europepmc.org/article/med/786739
How to contact Alex Johnstone:
Twitter: @Dr_A_Johnstone
Email: alex.johnstone@abdn.ac.uk
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