David Rönnlid Podcast – Details, episodes & analysis

🌍 How can we align our lives — and our societies — with our body clocks?

Poor sleep and circadian misalignment don’t just make us tired — they impair several aspects of our metabolic health. I sat down with Jonathan Cedernaes, M.D., Ph.D., and explored what we can do about it: from personal daily habits to systemic policy reforms. Sleep quality and quantity isn’t just about recovery — it’s a public health issue.

We dive deep into:

✅ Daily habits that keep your circadian rhythm aligned

✅ Why sleep timing is as important as sleep duration

✅ How late nights and irregular schedules impair metabolism and long-term health

✅ Policy changes that could protect circadian health at a population level — from school start times to shift work regulations

✅ The promise of circadian science for future treatments and prevention strategies

💡 What do you think matters more for our collective health: better personal habits or policy reforms?

#SleepScience #CircadianHealth #Metabolism #PublicHealth

Sleep science group: https://www.facebook.com/groups/495466987134152/

Connect with Jonathan on social media:

X: https://x.com/jcedernaes

IG: https://www.instagram.com/sleepydrcedernaesclocks/

Episode chapters:

00:00:00 Introduction

00:02:05 Sleep as a Driver of Motivation and Healthy Habits

00:04:15 Weekend Catch-Up Sleep: Benefits and Limits

00:07:50 Sleep, Metabolic Health, and Obesity Links

00:10:13 Sleep Disruption and Neurodegenerative Disease

00:12:53 Mechanisms: How Neurodegeneration Impairs Sleep

00:18:30 Supplements, Exam Stress, and Slow-Wave Sleep

00:20:01 The Body's Master Clock in the Brain: The Suprachiasmatic Nucleus

00:23:20 Light, Retina, and the Body’s Internal Timekeeping

00:43:16 Late-Night Eating and Sleep Quality

00:46:00 Heart Rate Variability: What It Really Tells Us

00:52:10 Short Sleepers, Long Sleepers, and Individual Needs

01:05:22 Circadian Misalignment: Jet Lag and Shift Work

01:19:44 Sleep and Mental Health Connection

01:33:11 Diet Timing, Fasting, and Circadian Rhythm

01:43:52 Exercise After Sleep Loss: Helpful or Harmful?

01:56:20 MicroRNAs, Sleep Loss, and Neurodegeneration Risk

02:14:36 AI, Research, and Sleep Science in the Future

02:22:06 Summary of most important takeaways from the conversation

Most of us think of different types of cholesterol as either “good” or “bad.” But the reality is more complex.

Daniel Elías-López, Endocrinologist, Ph.D, is a Mexican endocrinologist and researcher whose work spans both clinical care and public health. After years of treating patients with obesity, diabetes, and lipid disorders, he saw a limit to what could be achieved in the clinic alone. That realization led him toward research—with work aimed at generating knowledge that could inform prevention and treatment strategies for millions.

In this episode, we discuss:

- Why LDL is only part of the picture

- How elevated cholesterol can remain asymptomatic for years, and why early measurement is important for timely risk detection

- Practical, evidence-based strategies that can help lower risk for cardiovascular events

Rather than claiming to have all the answers, Dr. Daniel Elías-López shares his insights from clinical experience and research —highlighting what’s known, what’s emerging, and why prevention matters.

You can connect with Dr. Daniel Elías-López on LinkedIn: https://www.linkedin.com/in/danieleliasl/ and listen to his podcast in Spanish: https://open.spotify.com/show/31RDgmiIWXQHyHNjgBxeNe?si=6bdf7f42589f4af6

Episode chapters:

00:00:00 - Why lipoproteins are essential for human health

00:07:14 - Research motivation behind studying cholesterol particles

00:14:53 - How lipoprotein particle size affects heart risk

00:22:00 - The main types of cholesterol in the body

00:29:40 - Understanding non-HDL cholesterol and health impacts

00:36:50 - Genetics and their influence on lipid metabolism

00:44:02 - Strategies to improve current cholesterol guidelines

00:51:41 - How cholesterol knowledge translates to clinical practice

00:58:49 - Fasting versus non-fasting lipid blood testing

01:06:29 - What cholesterol levels really tell about health

01:13:40 - Additional lipid markers for cardiovascular assessment

01:20:55 - Current debates in cholesterol research and policy

01:28:30 - Impact of diet on lipid profile and heart health

01:36:10 - Future directions in lipid research and prevention

01:43:55 - Key takeaways and summary of cholesterol insights

In this episode, I talk with Gabriel Baldanzi, PhD, M.D., and Koen Dekkers, Research Assistant, who work in the same research group at Uppsala University. They are both actively researching the role of the gut microbiome in human health and chronic disease.

Studies discussed in this episode:

1. ​Dekkers, K.F., Sayols-Baixeras, S., Baldanzi, G. et al. An online atlas of human plasma metabolite signatures of gut microbiome composition. Nature Communications 13, 5370 (2022).
2. ​Baldanzi, Gabriel et al. Accelerometer-based physical activity is associated with the gut microbiota in 8416 individuals in SCAPIS. eBioMedicine, Volume 100, 104989.
3. ​Baldanzi, Gabriel et al., OSA Is Associated With the Human Gut Microbiota Composition and Functional Potential in the Population-Based Swedish CardioPulmonary bioImage Study. CHEST, Volume 164, Issue 2, 503 - 516.

Gutsy atlas link⁠.

Episode chapters:

00:00 Introduction to the episode and guest researchers, discussing the role of the gut microbiome in chronic diseases.

06:00 Overview of how bacteria in the gut impact health, immune response, and metabolism.

09:24 Methods used in the study, focusing on shotgun metagenomics and its advantages.

10:01 The relationship between gut microbiota-derived metabolites like TMAO and cardiovascular risk.

12:11 Explanation of metagenomics methods used in the study to measure gut microbiome.

18:09 Overview of the study’s large sample size and its unique approach.

20:44 Health Implications of Butyrate

21:37 Fiber’s Role in Butyrate Production

23:32 Diet and Gut Microbiome Diversity

27:18 Fiber Intake and Gut Health

30:19 Alpha Diversity in the Gut Microbiome

37:05 Microbiome Diversity and Type 2 Diabetes

44:00 Future of Microbiome Sampling Techniques: Capsule Innovations

45:04 Exploring Rare and Uncatalogued Species

47:02 The Role of AI in Gut Microbiome Research

50:00 Selecting Metabolites for Research Focus & Gutsy Atlas

01:00:11 Coffee Metabolites and Their Variance

01:00:40 Interpreting Associations between Coffee Metabolites and Gut Microbiota Variety and Specific Species

01:06:27 Streptococcus salivarius and Coffee Metabolites

01:10:31 Plasma Nucleotides and Gut Microbiome

01:12:12 Physical Activity and Gut Microbiome Diversity

01:14:55 Dietary Fiber and Gut Microbiome Diversity

01:15:53 Physical Activity and Its Impact on Gut Health

01:16:46 Physical Activity, Adiposity, and Microbiome Diversity

01:19:25:12 Genetic Predisposition and Physical Activity Effects

01:22:14 Gut Microbiota and Exercise Enjoyment

01:22:55 Gut-Brain Axis and Exercise

01:23:43 Lactate-consuming Bacteria in Marathon Runners

01:25:23 Gut Microbiota and Physical Activity Habits

01:25:51 Sedentary Behavior and GABA-producing E. coli Abundance

01:27:36 Gut Microbiota’s Effect on Behavior

01:28:40 Vagus Nerve and Gut Microbiota Influence

01:30:07 Fecal Transplants and Mood Enhancement

01:32:47 Colonization Resistance and Probiotics, The Long-Term Effects of Supplementing Gut Bacteria

01:37:28 Factors Influencing Probiotic Retention

01:38:47 Risks of Probiotics Competing with Native Species

01:43:36 What Diet is Best for Promoting a Healthy Gut Microbiome

01:45:30 Obstructive Sleep Apnea and the Gut Microbiome

01:47:58 Hypoxia and its Impact on the Gut Microbiome, Including by Altering Lactate and Propionate Metabolism

02:00:07 Cognitive Performance and the Gut Microbiome

02:00:31 Upcoming Large Microbiome Studies

02:01:08 Preliminary Findings in Microbiome and Cognition

02:06:45 Current Microbiome Tests for Consumers on the Commercial Market

02:10:50 Antibiotic Use and Its Long-Term Effects on the Microbiome

02:13:22 Conclusion and Thanks

Please beware of the risks of exposing your skin to sunlight in general and UVA light in particular. A large body of evidence suggests that UVA light exposure on the skin can increase risk for various skin cancers. This podcast episode is not intended as a recommendation to increase your personal amount of time spent in the sun. The decision of how much sunlight to expose your skin to is yours to make. This podcast episode is intended to raise awareness of only some of the effects of UVA in order to help you make that decision an informed decision. So, in the name of increasing awareness of all of the effects of sunlight on human health, please take into consideration not only the potential positive psychological effects that were mentioned in this episode, but also some established harmful somatic effects of UVA light:

https://www.skincancer.org/risk-factors/uv-radiation/

Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC113771/

Study reference: Gambichler T, et al. Impact of UVA exposure on psychological parameters and circulating serotonin and melatonin.

BMC Dermatol. 2002 Apr 12;2:6. doi: 10.1186/1471-5945-2-6. PMID: 11952999; PMCID: PMC113771.

Study link: https://www.mdpi.com/1660-4601/17/16/5859

Study reference:

Nunes, J.P., et al.

Placing Greater Torque at Shorter or Longer Muscle Lengths? Effects of Cable vs. Barbell Preacher Curl Training on Muscular Strength and Hypertrophy in Young Adults. 

Int. J. Environ. Res. Public Health 2020, 17, 5859.

https://doi.org/10.3390/ijerph17165859

Study link: https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2021.659990

Study reference:

Chauvineau Maxime , et al.

Effect of the Depth of Cold Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners

Frontiers in Sports and Active Living. Volume 3. 2021. ⁠https://doi.org/10.3389/fspor.2021.659990⁠

Related episodes from the Exploring Health and Medicine podcast:

• #1: Christian Benedict - How to measure and improve your sleep
• Does ambient temperature impact sleep quantity or quality? | Mental health monologue #6
  

Per Hall is a professor at the Department of Medical Epidemiology and Biostatistics at Karolinska Institute in Stockholm. He is also a senior physician at Södersjukhuset.

His breast cancer research is focused on prevention and early detection.

Timestamps:

00:00 Why breast cancer prevention is important

01:35 Breast Cancer Statistics in Sweden and Worldwide

03:01 Breast Cancer in Males and Age-Related Incidence

05:17 Breast Cancer Screening Programs

07:20 Risk-Based Screening vs. Age-Based Screening

12:21 AI and Machine Learning in Breast Cancer Detection

22:36 Contrast-Enhanced Mammography

29:30 Tamoxifen and Endoxifen for Breast Cancer Prevention

31:07 Tamoxifen's Side Effects and Patient Compliance

31:55 Testing Lower Doses of Tamoxifen

33:27 Endoxifen: A Promising Alternative

34:55 Study Results and Side Effects

37:34 Future Screening Programs and Endoxifen

41:27 Modifiable Risk Factors for Breast Cancer

53:39 Self-Examination and Screening Importance

57:48 How to Properly Self-Examine Your Breasts

Practical takeaways from the study are summarized at the beginning of the episode (00:00 - 04:30).

Study link: https://www.sciencedirect.com/science/article/pii/S1087079224000194 Study reference: Guillaume Chevance, et al.

A systematic review of ambient heat and sleep in a warming climate,

Sleep Medicine Reviews, Volume 75, 2024, 101915, ISSN 1087-0792, https://doi.org/10.1016/j.smrv.2024.101915.

Lena Flyckt is an associate professor at the Department of Clinical Neuroscience at Karolinska Institutet in Stockholm, Sweden.

She is recognized for her research in psychiatry, including on schizophrenia and the effects of the condition on caregivers surrounding the patient.

Lena also has more than 30 years of experience working clinically as a psychiatrist, including with many people who have schizophrenia.

Christian Benedict, PhD, is a sleep researcher at Uppsala University in Sweden.

He is known for his ability to communicate the importance of sleep in both academic and public settings, advocating for sleep as a key factor in maintaining health and productivity.

Follow Christian on InstaGram: https://www.instagram.com/sleep_advocate/

Buy Christians book (Swedish version): https://www.bokus.com/bok/9789178876402/sov-dig-till-ett-battre-liv-vad-andning-sex-melatonin-tyngdtacke-fullmane-och-kiwi-kan-gora-for-din-somn/?fbclid=PAZXh0bgNhZW0CMTEAAaZwBdKTFb1SZhUgw7jfrZvADGzF67tcfJqQJVDi5b6OOXr8xt3Nv-dMLac_aem_ef109znbPXFYsN2nMw8UYQ