CHRONO:MEDICINE

In the second part with Prof. Satchidananda (Satchin) Panda (Regulatory Biology Laboratory at the Salk Institute for Biological Studies in La Jolla, California), we continue talking about breakthrough discoveries from past years of him and other chronobiologists. First, we discuss how the timing of medication intake could help in optimizing its effects. Then, Satchin shares his perspective on ongoing developments in the lighting industry since the discovery of the blue-light sensitive melanopsin. In both contexts, we also discuss self-limiting features of chronobiology and circadian rhythms research that may stand in the way of using chronobiological principles to achieve policy changes in clinical practice and that should ideally be overcome to collaborate better with other medical disciplines as well as the industry. Lastly, Satchin shares his simple way of measuring scientific success.Chapters:(00:01:14) Intro(00:03:00) Timing medicines(00:08:18) Self-limiting features of chronobiology(00:15:56) Wearable technologies and chronobiology(00:20:22) More engagement with other disciplines(00:29:00) Daylight-mimicking electric light(00:34:04) Funny anecdote(00:37:45) How to measure scientific success?(00:41:07) Satchin’s book and podcast(00:45:09) OutroStudies that Satchin refers to:John Hogenesch timing of drugs paper:“Dosing time matters”https://doi.org/10.1126/science.aax7621 “Clocks, cancer, and chronochemotherapy”https://doi.org/10.1126/science.abb0738 “Could a good night's sleep improve COVID-19 vaccine efficacy?”https://doi.org/10.1016/S2213-2600(21)00126-0“Biological rhythms in COVID-19 vaccine effectiveness in an observational cohort study of1.5 million patients”https://doi.org/10.1172/JCI167339 Timing of pain medication intake at evening or bedtime to manage pain in the morning:“Bedtime Single-Dose Prednisolone in Clinically Stable Rheumatoid Arthritis Patients”https://doi.org/10.5402/2012/637204 TRF increases the robustness and numbers of genes that cycle:“Time of feeding and the intrinsic circadian clock drive rhythms in hepatic gene expression”https://doi.org/10.1073/pnas.0909591106“Diurnal transcriptome landscape of a multi-tissue response to time-restricted feeding in mammals”https://doi.org/10.1016/j.cmet.2022.12.006 CRY double knockout mice still have metabolic rhythms upon TRF:“Time-Restricted Feeding Prevents Obesity and Metabolic Syndrome in Mice Lacking a Circadian Clock”https://doi.org/10.1016/j.cmet.2018.08.004 “A Free-Choice High-Fat High-Sugar Diet Alters Day–Night Per2 Gene Expression in Reward-Related Brain Areas in Rats”https://doi.org/10.3389/fendo.2018.00154 “Repeated exposures to daytime bright light increase nocturnal melatonin rise and maintain circadian phase in young subjects under fixed sleep schedule”https://doi.org/10.1152/ajpregu.00211.2006“Bright light exposure during the daytime affects circadian rhythms of urinary melatonin and salivary immunoglobulin A”https://doi.org/10.3109/07420529909116864“Positive effect of daylight exposure on nocturnal urinary melatonin excretion in the elderly: A cross‑sectional analysis of the HEIJO‑KYO study”https://doi.org/10.1210/jc.2012-1873 Satchin’s melanopsin discovery paper:“Melanopsin (Opn4) Requirement for Normal Light-Induced Circadian Phase Shifting”https://doi.org/10.1126/science.1076848 The Economist article “Light therapeutics”:https://www.economist.com/1843/2014/12/29/the-light-therapeutic?utm_campaign=shared_article Amandine Chaix paper that TRF is both preventative and therapeutic, 5 days TRF and 2 days not:“Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges”https://doi.org/10.1016/j.cmet.2014.11.001Satchin’s resources:His book: “The Circadian Code”His podcast: “Performance around the clock” (also on Spotify)“MyCircadianClock” appPanda Lab homepage: ⁠https://panda.salk.edu/⁠ 

As the third spotlight for the European Biological Rhythms Society (EBRS) congress, taking place in Luebeck in Northern Germany from the 24th to 28th of August 2025, Prof. Satchidananda (Satchin) Panda (Regulatory Biology Laboratory at the Salk Institute for Biological Studies in La Jolla, California) talks about several breakthrough discoveries from past years of him and other chronobiologists. In this first part, Satchin explains the relevance of time-restricted eating (TRE) with people nowadays eating around the clock and how he faced a lot of pushback from the nutrition field after his initial discovery of TRE's health benefits in mice. We discuss how food photos eventually helped him move forward with his research. He also tells us about his memories from attending previous EBRS congresses and why you should join this year. Lastly, Satchin shares some rather unique advice for early-career researchers.Chapters:(0:00:40) Intro(0:05:52) Satchin Panda(0:09:03) People eat around the clock(0:20:35) Analyzing food photos (0:30:59) Is late eating or reduced fasting the problem?(0:44:00) Diurnal changes in glucose tolerance(0:49:07) EBRS congress memories(0:56:57) Advice for early-career researchers(1:05:48) Outro & Teaser to Part 2Studies that Satchin refers to:Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet (Hatori et al. 2012)https://www.sciencedirect.com/science/article/pii/S1550413112001891A Smartphone App Reveals Erratic Diurnal Eating Patterns in Humans that Can Be Modulated for Health Benefits (Gill & Panda 2015)https://pubmed.ncbi.nlm.nih.gov/26411343/Feasibility of time-restricted eating and impacts on cardiometabolic health in 24-h shift workers: The Healthy Heroes randomized control trial (Manoogian et al. 2022)https://doi.org/10.1016/j.cmet.2022.08.018Satchin’s resources:His book: “The Circadian Code”His podcast: “Performance around the clock” (also on Spotify)“MyCircadianClock” appPanda Lab homepage: https://panda.salk.edu/ 

As the second spotlight for the European Biological Rhythms Society - EBRS - congress, taking place in Luebeck in Northern Germany from the 24th to 28th of August 2025, Prof. Henriette Uhlenhaut (Professor of Metabolic Programming at the Technical University of Munich, TUM, and Director of the Institute for Diabetes and Endocrinology at the Helmholtz Center in Munich) talks about glucocorticoids (such as cortisol), commonly known as the "stress hormones". We discuss how glucocorticoids regulate gene expression at many different sites within our body and how they play different roles in metabolism, immune responses and inflammation. We highlight that glucocorticoids are secreted in a strongly circadian manner and describe which kind of events can acutely increase cortisol levels independent of rhythmic secretion. In contrast to common belief, Henriette explains why high cortisol levels are not always a bad thing, highlighting important links to fasting and caloric restriction. Lastly, Henriette shares her experience attending previous EBRS congresses and why you should consider joining it this year. Chapters:(0:00:38) Introducing the EBRS 2025 spotlights(0:03:39) Henriette Uhlenhaut(0:06:08) Basics of glucocorticoids(0:16:26) Circadian rhythm of glucocorticoids(0:23:21) How to shift the rhythm?(0:28:49) What events evoke a cortisol response?(0:36:45) Stress hormones - a fair description?(0:39:08) Cortisol vs. melatonin(0:42:16) Link to caloric restriction(0:50:25) EBRS experience(0:53:45) EBRS teaser(0:56:30) Advice for early career researchers(1:00:28) Funny anecdote(1:06:35) Outro Studies that Henriette and I refer to:Studies on the % of genes that are regulated by glucocorticoids (liver, immune cells etc.): https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.0010016 https://pmc.ncbi.nlm.nih.gov/articles/PMC2792167/ https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2020.572981/full  Glucocorticoids universally regulate clock genes such as Per1 inevery cell type: https://doi.org/10.1093/emboj/20.24.7128https://doi.org/10.1210/en.2012-1486 The more fasted you are, the higher your cortisol levels: https://doi.org/10.3109/10253890.2015.1121984 Light stimulates ACTH secretion = activation of thehypothalamic-pituitary-adrenal axis: https://academic.oup.com/edrv/article/41/3/bnaa002/5736359 Shifting the last meal of the day shifts cortisol secretion: https://pmc.ncbi.nlm.nih.gov/articles/PMC5483233/ Shifting sleep time shifts cortisol secretion: https://pmc.ncbi.nlm.nih.gov/articles/PMC11899833/ If the feeding time of mice is reversed, there are two peaks incorticosterone secretion: one peak driven by the central clock, and one driven by food availability: https://www.embopress.org/doi/full/10.1093/emboj/20.24.7128 Exercise can change cortisol secretion, also locally in tissues: https://link.springer.com/article/10.2165/00007256-200535050-00003#Sec4 https://journals.physiology.org/doi/full/10.1152/japplphysiol.00108.2002 Maternal stress impacts the newborn: https://doi.org/10.1016/j.biopsych.2010.05.028 Caloric restriction boosts the cortisol amplitude: https://www.cell.com/cell-reports/fulltext/S2211-1247(15)01483-7 Symptoms of rheumatoid arthritis, cough and fever show 24-hourrhythms: https://link.springer.com/chapter/10.1007/978-3-642-78734-8_35 https://www.sciencedirect.com/science/article/pii/S0091674995702121#bib27 https://www.tandfonline.com/doi/abs/10.3109/07420528809067786 Beyond 12 to 14 hours of fasting, ketone bodies are built based on liver fat and adipose tissue: https://link.springer.com/article/10.1007/s10545-014-9704-9 https://www.cell.com/trends/endocrinology-metabolism/fulltext/S1043-2760(23)00215-1  Ketogenic diet on rhythmicity in transcriptomes of metabolic organshttps://www.ncbi.nlm.nih.gov/pubmed/28877456 Contact:Henriette’s research group homepage: https://www.mls.ls.tum.de/metabolism/home/

In collaboration with the organizers of the 18th Congress of the European Biological Rhythms Society - EBRS - taking place in Luebeck 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.Chapters:(0:00:39) Introducing the EBRS 2025 spotlights(0:03:51) Michael Hastings(0:07:17) Circatidal ryhthms(0:14:38) The central clock or SCN(0:24:47) Different zeitgebers(0:35:17) Melatonin(0:46:14) Melatonin as a sleeping aid(0:51:38) EBRS congress experience(0:58:22) Career advice(1:10:02) Funny anecdote(1:13:54) OutroStudies that Michael refers to:Reviews on circatidal rhythmshttps://doi.org/10.1016/j.cub.2008.06.041https://doi.org/10.1016/j.tig.2024.01.006 Prevalence of mutations in clock genes to make the period length shorter or longer than approx. 24 hours, rare familial sleep disordershttps://doi.org/10.1038/s41386-019-0476-7 Mice mutations support that the same enzymes are involved as in the human sleep disordershttps://www.nature.com/articles/s41583-018-0026-z Period genes in the SCN are activated by lighthttps://doi.org/10.1016/S0092-8674(00)80494-8 Caffeine can phase shift the circadian clockhttps://doi.org/10.1126/scitranslmed.aac5125 Manipulation of NPY and serotonin can shift the SCN clock https://doi.org/10.1152/ajpregu.00320.2022 Human cortisol levels increase before awakening in anticipation of wakehttps://doi.org/10.1677/JOE-07-0378 Temperature in the physiological range can act as a zeitgeber to entrain peripheral clockshttps://doi.org/10.1016/S0960-9822(02)01145-4 When interfering with neuropeptide levels within the SCN, you can entrain the SCN with temperature cycleshttps://doi.org/10.1126/science.1195262 High levels of estradiol make the SCN run fasterhttps://doi.org/10.1126/science.557840 Melatonin is a transplacental zeitgeberhttps://pubmed.ncbi.nlm.nih.gov/3780553/https://doi.org/10.1177/074873049701200603 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)https://link.springer.com/article/10.1007/s00441-002-0576-1 GWAS papers: variance of melatonin receptor are related to the type 2 diabetes andmetabolic disordershttps://www.nature.com/articles/ng.277https://www.nature.com/articles/s41574-018-0130-1Contacting Michael Hastings:Homepage: https://www2.mrc-lmb.cam.ac.uk/group-leaders/h-to-m/michael-hastings/Email: ⁠[email protected]⁠EBRS homepage:https://www.ebrs-online.org

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 lifespanhttps://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 ?https://jcsm.aasm.org/doi/10.5664/jcsm.7128 Sleep apnea: Spotlight article with Jesse Cooks and Jonathan Cedernaeshttps://pubmed.ncbi.nlm.nih.gov/33180697/ Lancet Respiratory Medicine review, 425 million people suffer from moderate to severeobstructive sleep apneahttps://pubmed.ncbi.nlm.nih.gov/31300334/ Ad-hoc sleep apnea screening in patients admitted to the hospital, 80% are not aware of ithttps://pubmed.ncbi.nlm.nih.gov/19186102/ Australian study using a measurement pillow to track sleep apneahttps://www.atsjournals.org/doi/full/10.1164/rccm.202107-1761OC Christian’s work (2015) those who have over 40 years regular sleep problems have an increased risk for Alzheimer’shttps://pubmed.ncbi.nlm.nih.gov/25438949/ Studies comparing people with kids and without kids, those with kids live longerhttps://jech.bmj.com/content/71/5/424  How to contact Christian Benedict:Email: [email protected]: https://www.linkedin.com/in/christian-benedict-a25b1615a/