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) Outro
Studies 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.2014.11.001
Satchin’s resources:
His book: “The Circadian Code”
His podcast: “Performance around the clock” (also on Spotify)
“MyCircadianClock” app
Panda 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 2
Studies 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/S1550413112001891
A 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.2022.08.018
Satchin’s resources:
His book: “The Circadian Code”
His podcast: “Performance around the clock” (also on Spotify)
“MyCircadianClock” app
Panda Lab homepage: https://panda.salk.edu/
As the second spotlight for the European Biological Rhythms Society (EBRS) congress (taking place in Lübeck in NorthernGermany 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. Wehighlight 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 whyhigh 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 byglucocorticoids (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/20.24.7128
https://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 organs
https://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 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.
EBRS homepage: https://ebrs-online.org/index.php/events/ebrs2025.html
Chapters:
(0:00:39) Introducing the EBRS 2025 spotlights
(0:03:51) Michael Hastings
(0:07:17) Circatidal rhythms
(0:14:38) The central clock / 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) Michael’s career advice
(1:10:02) Funny anecdote
(1:13:54) Outro
Studies that Michael refers to:
Reviews on circatidal rhythms
https://doi.org/10.1016/j.cub.2008.06.041
https://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 disorders
https://doi.org/10.1038/s41386-019-0476-7
Mice mutations support that the same enzymes are involved as in the human sleep disorders
https://www.nature.com/articles/s41583-018-0026-z
Period genes in the SCN are activated by light
https://doi.org/10.1016/S0092-8674(00)80494-8
Caffeine can phase shift the circadian clock
https://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 wake
https://doi.org/10.1677/JOE-07-0378
Temperature in the physiological range can act as a zeitgeber to entrain peripheral clocks
https://doi.org/10.1016/S0960-9822(02)01145-4
When interfering with neuropeptide levels within the SCN, you can entrain the SCN with temperature cycles
https://doi.org/10.1126/science.1195262
High levels of estradiol make the SCN run faster
https://doi.org/10.1126/science.557840
Melatonin is a transplacental zeitgeber
https://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 disorders
https://www.nature.com/articles/ng.277
https://www.nature.com/articles/s41574-018-0130-1
Contacting Michael Hastings:
Homepage: https://www2.mrc-lmb.cam.ac.uk/group-leaders/h-to-m/michael-hastings/
Email: mha@mrc-lmb.cam.ac.uk
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 ?
https://jcsm.aasm.org/doi/10.5664/jcsm.7128
Sleep apnea: Spotlight article with Jesse Cooks and Jonathan Cedernaes
https://pubmed.ncbi.nlm.nih.gov/33180697/
Lancet Respiratory Medicine review, 425 million people suffer from moderate to severeobstructive sleep apnea
https://pubmed.ncbi.nlm.nih.gov/31300334/
Ad-hoc sleep apnea screening in patients admitted to the hospital, 80% are not aware of it
https://pubmed.ncbi.nlm.nih.gov/19186102/
Australian study using a measurement pillow to track sleep apnea
https://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’s
https://pubmed.ncbi.nlm.nih.gov/25438949/
Studies comparing people with kids and without kids, those with kids live longer
https://jech.bmj.com/content/71/5/424
How to contact Christian Benedict:
Email: Christian.benedict@farmbio.uu.se
LinkedIn: https://www.linkedin.com/in/christian-benedict-a25b1615a/
Dr. Christian Benedict (Senior Lecturer & Associate Professor at the Department of Pharmaceutical Biosciences, Research and Pharmacology at Uppsala University, Sweden) talks about how to study sleep and its relevance for our overall health. In this first part, Christian introduces us to different definitions of sleep. Together, we try to decipher the concept of sleep quality or in other words how to judge if somebody had a good night’s sleep or not. Christian also summarizes the research around the optimal duration of sleep and discusses the relevanceof spending time in different sleep stages.
Chapters:
(0:00:12) Intro
(0:03:41) Christian Benedict’s career path
(0:13:06) What is sleep?
(0:24:09) Sleep stages & sleep quality
(0:34:06) Sleep quantity/duration
(0:42:08) Outro & Teaser to Part 2
Studies that Christian refers to:
Aversive tobacco smoke during non-REM sleep
https://pubmed.ncbi.nlm.nih.gov/25392505/
Epileptic patients and sleep deprivation
https://pubmed.ncbi.nlm.nih.gov/29106402/
Correlations between time in different sleep stages and daytime alertness are not that good, contradictory evidence
https://pubmed.ncbi.nlm.nih.gov/10678518/
Epworthsleepiness scale and sleep stages are not well correlated
https://pubmed.ncbi.nlm.nih.gov/19110886/
People struggling with sleep do not necessarily differ in PSG-derived sleep stage outcomes from normally sleeping people
https://pubmed.ncbi.nlm.nih.gov/29402512/
Peer feedback can impact your retrospective judgement of your last night of sleep
https://pubmed.ncbi.nlm.nih.gov/24417326/
https://pubmed.ncbi.nlm.nih.gov/33204201/
American Society for Sleep Medicine, 7-9 hours, probably 6 and 10 hours are also fine
https://www.thensf.org/wp-content/uploads/2020/10/NSF-SleepDurationTiming_Background-1200x1312-1.jpg
Shorter or longer than these 6-10 hours is mostly associated with poor health outcomes
https://pubmed.ncbi.nlm.nih.gov/11825133/
Christian’s work on interindividual responses in brain health outcomes to sleep loss
https://pubmed.ncbi.nlm.nih.gov/36088460/
Studies showing that people who think they cope well with sleep loss are actually not doing well
https://pubmed.ncbi.nlm.nih.gov/29383809/
How to contact Christian Benedict:
Email: Christian.benedict@farmbio.uu.se
LinkedIn: https://www.linkedin.com/in/christian-benedict-a25b1615a/
In the second part with Prof. Christian Cajochen (Head of the Centre for Chronobiology at the University of Basel in Switzerland), contributing to the Daylight Awareness Week (28th of October - 2nd of November 2024), we continue our discussion around the impact of daylight on our health, with a special focus on sleep. Christian summarizes the negative effects of bright electric light exposure on sleep and other health outcomes. On the other hand, he highlights the importance of daylight and alternatively increased electric light intensities during daytime for sleep. We also discuss how seasonal changes in daylight affect us more than we think. Christian gives insights into a real-world example of how switching to dynamic lighting at the workplace changed people’s wellbeing. And lastly, we discuss if a medical pill could eventually replace the health effects of daylight.
More information about the Daylight Awareness Week: https://daylight.academy/daylight-awareness-week-2024/
Chapters:
(0:00:12) Intro & Daylight Awareness Week
(0:00:48) Topics of this episode series
(0:02:13) Introduction to sleep
(0:04:15) Evening electric light & sleep
(0:09:42) Daylight & sleep
(0:15:47) Seasonal effects of daylight
(0:20:33) Can higher light intensities during daytime reduce negative effects of evening light?
(0:25:47) How to tackle the lack of daylight as a society?
(0:36:00) Take-home message on daylight & health
(0:37:39) Christian’s career goals & future research
(0:41:15) Funny anecdotes
(0:47:18) Outro & Teaser to Part 2
Studies that Christian refers to: Evening administration of melatonin and bright light: Interactions on the EEG during sleep and wakefulness
https://doi.org/10.1046/j.1365-2869.1998.00106.x
Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers
https://doi.org/10.1016/j.jadohealth.2014.08.002
Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study)
https://doi.org/10.1289/EHP1837
Camping Study: “Circadian Entrainment to the Natural Light-Dark Cycle across Seasons and the Weekend”
Effect of daylight LED on visual comfort, melatonin, mood, waking performance and sleep
https://doi.org/10.1177/1477153519828419
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
Effect of Bright Light and Melatonin on Cognitive and Noncognitive Function in Elderly Residents of Group Care Facilities: A Randomized Controlled Trial
https://doi.org/10.1001/jama.299.22.2642
Preprint article: “Sex and seasonal variations in melatonin suppression, and alerting response to light”
https://doi.org/10.1101/2024.10.18.619012
Light therapy in non-seasonal depression: An update meta-analysis
https://doi.org/10.1016/j.psychres.2020.113247
Pre-print article: “Afternoon to early evening bright light exposure reduces later melatonin production in adolescents”
https://doi.org/10.1101/2024.10.02.616112
Regular Caffeine Intake Delays REM Sleep Promotion and Attenuates Sleep Quality in Healthy Men
https://doi.org/10.1177/07487304211013995
Evidence that the Lunar Cycle Influences Human Sleep
How to contact Christian Cajochen:
Email: Christian.Cajochen@upk.ch
Twitter: @ollen44
LinkeIn: https://www.linkedin.com/in/christian-cajochen-1435258/
As part of the Daylight Awareness Week (28th of October - 2nd of November 2024), Prof. Christian Cajochen (Head of the Centre for Chronobiology at the University of Basel in Switzerland) talks about the impact of daylight on our health, with a special focus on sleep. In the first part, we talk about the importance of light for the circadian timing system within our bodies, with melatonin playing an important role. Christian explains why light can have very different effects on our health depending on the time of day of light exposure, and highlights the most important time to see daylight. Christian points out the benefits of daylight particularly for older people. We also critically discuss how difficult it is to study the health effects of daylight without any confounding from other "side-benefits" outdoors. And lastly, we discuss the effects of light on our cardiovascular system (like heart rate and blood pressure) as well as alertness.
More information about the Daylight Awareness Week: https://daylight.academy/daylight-awareness-week-2024/
Chapters:
(0:00:12) Intro & Daylight Awareness Week
(0:02:10) Topics of this episode series
(0:03:33) Introducing Christian Cajochen
(0:08:21) Daylight vs. electric light
(0:13:28) Circadian clocks & melatonin
(0:20:31) Wavelength dependency
(0:23:13) Timing of light matters
(0:30:43) How to study health effects of daylight without confounders?
(0:38:32) Light & Cardiovascular health
(0:45:31) Warm feet to promote sleep
(0:52:14) Light & Blood pressure
(0:56:11) Outro & Teaser to Part 2
Studies that Christian refers to:
The aging clock: circadian rhythms and later life
https://doi.org/10.1172/JCI90328
A Phase Response Curve to Single Bright Light Pulses in Human Subjects
https://doi.org/10.1113/jphysiol.2003.040477
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
The biological clock tunes the organs of the body: timing by hormones and the autonomic nervous system
https://doi.org/10.1677/joe.0.1770017
Light activates the adrenal gland: Timing of gene expression and glucocorticoid release
Warm feet promote the rapid onset of sleep
https://www.nature.com/articles/43366
Functional link between distal vasodilation and sleep-onset latency?
https://doi.org/10.1152/ajpregu.2000.278.3.R741
Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men
https://doi.org/10.1111/jpi.12714
Circadian mechanisms of 24-hour blood pressure regulation and patterning
https://doi.org/10.1016/j.smrv.2016.02.003
Alerting effects of light
https://doi.org/10.1016/j.smrv.2007.07.009
How to contact Christian Cajochen:
Email: Christian.Cajochen@upk.ch
Twitter: @ollen44
LinkeIn: https://www.linkedin.com/in/christian-cajochen-1435258/
After discussing in the first part how caloric restriction can extend lifespan, Dr. Victoria Acosta-Rodriguez (Leader of the Circadian Biology of Aging Unit at the National Institute on Aging (NIA), USA) talks in the second part about her recent study showing that eating these reduced calories always at a certain time of day extends the lifespan of mice even further. Beyond longevity, her study reveals that enhanced health benefits are achieved when feeding versus fasting times are aligned with the natural active and rest phase of mice as dictated by circadian clocks. In the end, we discuss the feasibility of long-term caloric restriction for humans and if similar health benefits could be expected in humans.
Chapters:
(00:00:45) Recap Part 1
(00:01:28) Part 2 topics
(00:02:09) Interview start
(00:03:28) Explaining the study design
(00:10:01) What kind of food did mice eat and why?
(00:13:56) Body weight changes over the lifespan
(00:15:58) Relevance of fasting duration
(00:19:45) A calorie is a calorie?
(00:22:47) The longest-lived mice
(00:25:49) Cause of death for 300 mice
(00:29:46) Physical activity as a survival predictor
(00:31:56) Body composition & metabolic health
(00:35:55) 48-hour liver samples
(00:47:18) Study limitations
(00:51:59) Monkey studies
(00:55:16) Feasibility of caloric restriction for humans
(00:59:21) Personal perspective
(01:09:00) Outro
Main study that we will discuss in depth:
Acosta-Rodriguez, V., Rijo-Ferreira, F., Izumo, M., Xu, P., Wight-Carter, M., Green, C.B., and Takahashi, J.S. (2022). Circadian alignment of early onset caloric restriction promotes longevity in male C57BL/6J mice. Science 376, 1192-1202. 10.1126/science.abk0297.
Additional papers that Victoria refers to:
Rhesus Monkeys - Caloric restriction & Lifespan
Mattison, J. A. et al. Impact of caloric restriction on health and survival in rhesus monkeys from the NIA study. Nature 489, 318–321 (2012).
Colman, R. J. et al. Caloric restriction reduces age-related and all-cause mortality in rhesus monkeys. Nat. Commun. 5, 3557 (2014).
Mattison, J. A. et al. Caloric restriction improves health and survival of rhesus monkeys. Nat. Commun. 8, 14063 (2017).
Humans -TRF
Sutton, E.F., Beyl, R., Early, K.S., Cefalu, W.T., Ravussin, E., and Peterson, C.M. (2018). Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metab 27, 1212-1221 e1213. 10.1016/j.cmet.2018.04.010.
Humans - CALERIE study
Martin, C. K. et al. Effect of calorie restriction on mood, quality of life, sleep, and sexual function in healthy nonobese adults: the CALERIE 2 randomized clinical trial. JAMA Intern. Med. 176, 743–752 (2016).
Das, S. K. et al. Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-year randomized controlled trial of calorie restriction in nonobese humans. Am. J. Clin. Nutr. 105, 913–927 (2017).
Mice – NIA Intervention Testing Program
https://www.nia.nih.gov/research/dab/interventions-testing-program-itp
Francesca Macchiarini, Richard A. Miller, Randy Strong, Nadia Rosenthal, David E. Harrison,
Chapter 10 - NIA Interventions Testing Program: A collaborative approach for investigating interventions to promote healthy aging, In Handbooks of Aging, Handbook of the Biology of Aging (Ninth Edition), Academic Press, 2021, Pages 219-235, ISBN 9780128159620,
https://doi.org/10.1016/B978-0-12-815962-0.00010-X
Contact: Dr. Victoria Acosta-Rodriguez
Email: victoria.acosta-rodriguez@nih.gov
Twitter/X: @VickyAcostaR
Dr. Victoria Acosta-Rodriguez (Leader of the Circadian Biology of Aging Unit at the National Institute on Aging (NIA), USA) talks about her research on longevity and caloric restriction. In this first part, Victoria introduces us to longevity research: what kind of interventions and drugs are known to promote longevity and why precise terminology separating life- and healthspan is important. We discuss how the lifespan of mice relates to the lifespan of humans and to what degree we can therefore translate mice studies to the human setting. As we will learn, one intervention to promote longevity is caloric restriction, that is why Victoria also summarizes our current understanding of caloric restriction and defines its different forms.
Chapters:
(00:00:45) Podcast name and host updates
(00:02:51) Introducing Victoria Acosta-Rodriguez
(00:04:43) Interview start
(00:05:26) Victoria’s personal background
(00:09:04) Terminology: Lifespan vs. healthspan
(00:12:25) What interventions promote longevity?
(00:17:24) Defining caloric restriction
(00:21:57) Relevance of feeding time for mice
(00:30:12) Mice vs. humans for longevity studies
(00:38:25) Changes in circadian rhythms upon aging?
(00:44:26) Outro
Main study that we will discuss in depth:
Acosta-Rodriguez, V., Rijo-Ferreira, F., Izumo, M., Xu, P., Wight-Carter, M., Green, C.B., and Takahashi, J.S. (2022). Circadian alignment of early onset caloric restriction promotes longevity in male C57BL/6J mice. Science 376, 1192-1202. 10.1126/science.abk0297.
Additional papers that Victoria refers to:
Mice - time-restricted feeding, regular chow
Damiola, F., Le Minh, N., Preitner, N., Kornmann, B., Fleury-Olela, F., and Schibler, U. (2000). Restricted feeding uncouples circadian oscillators in peripheral tissues from the central pacemaker in the suprachiasmatic nucleus. Genes Dev 14, 2950-2961.
Mice - on a high-fat diet & time-restricted feeding
Kohsaka, A., Laposky, A.D., Ramsey, K.M., Estrada, C., Joshu, C., Kobayashi, Y., Turek, F.W., and Bass, J. (2007). High-fat dietcdisrupts behavioral and molecular circadian rhythms in mice. Cell Metab 6, 414-421. 10.1016/j.cmet.2007.09.006.
Arble, D.M., Bass, J., Laposky, A.D., Vitaterna, M.H., and Turek, F.W. (2009). Circadian timing of food intake contributes to weight gain. Obesity (Silver Spring) 17, 2100-2102. 10.1038/oby.2009.264.
Vollmers, C., Gill, S., DiTacchio, L., Pulivarthy, S.R., Le, H.D., and Panda, S. (2009). Time of feeding and the intrinsic circadian clock drive rhythms in hepatic gene expression. Proc Natl Acad Sci U S A 106, 21453-21458. 10.1073/pnas.0909591106.
Hatori, M., Vollmers, C., Zarrinpar, A., DiTacchio, L., Bushong, E.A., Gill, S., Leblanc, M., Chaix, A., Joens, M., Fitzpatrick, J.A., et al. (2012). Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Cell Metab 15, 848-860. 10.1016/j.cmet.2012.04.019.
Mice -Calories, Fasting & important variables influencing Lifespan
Mitchell, S.J., Bernier, M., Mattison, J.A., Aon, M.A., Kaiser, T.A., Anson, R.M., Ikeno, Y., Anderson, R.M., Ingram, D.K., and de Cabo, R. (2019). Daily Fasting Improves Health and Survival in Male Mice Independent of Diet Composition and Calories. Cell Metab 29, 221-228 e223. 10.1016/j.cmet.2018.08.011.
Mitchell, S.J., Madrigal-Matute, J., Scheibye-Knudsen, M., Fang, E., Aon, M., Gonzalez-Reyes, J.A., Cortassa, S., Kaushik, S., Gonzalez-Freire, M., Patel, B., et al. (2016). Effects of Sex, Strain, and Energy Intake on Hallmarks of Aging in Mice. Cell Metab 23, 1093-1112. 10.1016/j.cmet.2016.05.027.
Acosta-Rodriguez, V.A., de Groot, M.H.M., Rijo-Ferreira, F., Green, C.B., and Takahashi, J.S. (2017). Mice under Caloric Restriction Self-Impose a Temporal Restriction of Food Intake as Revealed by an Automated Feeder System. Cell Metab 26, 267-277 e262. 10.1016/j.cmet.2017.06.007.
Acosta-Rodriguez, V.A., Rijo-Ferreira, F., Green, C.B., and Takahashi, J.S. (2021). Importance of circadian timing for aging and longevity. Nat Commun 12, 2862. 10.1038/s41467-021-22922-6.
Contact: Dr. Victoria Acosta-Rodriguez
Email: victoria.acosta-rodriguez@nih.gov
Twitter/X: @VickyAcostaR
From the 11th to the 13th of March 2024, the 247Muscle podcast has been invited to cover the ERATO UK - Japan Joint Symposium on Circadian rhythms & Sleep, which took place at the University of Oxford. The symposium aimed to promote research exchange and collaboration in the fields of sleep and circadian clocks between the UK and Japan. In this episode, your host Frieder summarizes scientific insights from the symposium and shares short interviews conducted with speakers during the symposium.
More information about the ERATO UK - Japan Joint Symposium: https://sys-pharm.m.u-tokyo.ac.jp/erato-uk/
Chapters:
(00:00:54) Background of the ERATO symposium
(00:02:40) Introduction by Hiroki Ueda
(00:07:25) Summary of the welcome ceremony
(00:10:03) Russell Foster on EEG and large sleep databases
(00:12:19) Wearables to measure sleep
(00:15:20) Andrew Millar on plant vs. human clocks and metabolism
(00:25:05) The concept of “Arrival” for circadian research
(00:36:35) Historical perspective on sleep research
(00:39:47) Anne Skeldon on mathematical models for sleep
(00:41:12) Koji Ode on CaMK2
(00:47:14) Hiroyuki Kanaya on anesthetics
(00:49:55) Akifumi Kishi on human sleep phenotypes
(00:50:44) Amin Mottahedin on stroke time
(00:53:01) Alex Webb on chronoculture and space culturing
(00:56:15) Sleep restriction therapy
(01:00:44) Attendants and organizers sharing their highlights
(01:07:48) Future perspective
(01:13:17) Closing remarks
(01:14:23) Sponsor: Mitsui Chemicals
(01:15:54) Outro
In this second part, Dr. John O'Neill (MRC Laboratory of Molecular Biology, Cambridge) provides deep insights from his recent study on how the timing of food intake mechanistically modifies circadian clocks in cells and animals. He explains the research journey of how his group identified systemic time cues associated with food intake. John highlights the indispensable role of the vital protein kinase called mTOR for the cell to process the timing of food intake. Lastly, we discuss how the mechanistic knowledge from John's research might translate to practical eating strategies for shiftwork and jetlag.
More information about the ERATO UK - Japan Joint Symposium: https://sys-pharm.m.u-tokyo.ac.jp/erato-uk/
Chapters:
(0:00:11) Intro
(0:02:23) Food-entrainable oscillator?
(0:06:06) How insulin emerged as a suspect
(0:08:38) Food timing entrains all cell clocks except for the SCN
(0:10:32) What other candidates than insulin were considered?
(0:12:29) How insulin modifies clocks
(0:16:35) Insulin action in vitro vs. in vivo
(0:25:07) Why the SCN remains mostly irresponsive to food timing
(0:31:13) How conflicting time cues impair circadian organization
(0:34:38) What about skipping breakfast?
(0:39:07) The role of meal frequency and snacking
(0:42:39) Combining time cues to support health
(0:45:37) The role of mTor in daily cellular timekeeping
(0:48:33) Translational perspective on shift work
(0:55:15) John’s recommendations to reduce jetlag
(0:58:05) John’s perspective on the ERATO symposium
(1:01:20) John’s future research
(1:05:20) John’s career ambitions
(1:08:01) Funny anecdote
(1:12:09) Outro
Dr. John O'Neill (MRC Laboratory of Molecular Biology, Cambridge), discusses his research focusing on the fundamentals of cellular timekeeping. In this first part, John explains the advantages of cells as a model to study circadian rhythms. He provides evidence of why we might consider questioning the current paradigm of how cells keep time, since his group for example demonstrated that even cells without nuclei show circadian rhythms. We further highlight a fascinating study in fibroblasts showing that wounds heal much faster when inflicted during the day vs. night. Lastly, John shares his knowledge of the vital protein kinase called mTOR, and its role in daily physiology.
More information about the ERATO UK - Japan Joint Symposium: https://sys-pharm.m.u-tokyo.ac.jp/erato-uk/
Chapters:
(0:00:28) Introducing ERATO UK/Japan Joint Symposium
(0:03:15) This episode’s guest and content
(0:05:43) Dr. John O’Neill introduces himself
(0:07:46) Advantages of cells as a model to study circadian rhythms
(0:11:11) Challenging our current understanding on how cells keep time
(0:18:47) How do known time cues translate into cellular signals?
(0:26:23) Almost or all cells in the human body have a clock?
(0:29:01) Day-night rhythms in wound healing
(0:37:02) mTOR’s role in physiology
(0:43:23) Activators and inhibitors of mTOR
(0:45:41) Daily and intrinsic rhythms in mTOR’s activity
(0:46:49) Outro
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.
More information about the Daylight Awareness Week: https://daylight.academy/daylight-awareness-week-2023/
Chapters:
(0:00:00) Intro & Recap of Part 1
(0:02:36) History of inventing fire & candles
(0:08:22) Rise of electric light & disruption
(0:15:15) Sensitivity to light at night
(0:22:03) Dominance of LEDs nowadays
(0:23:07) Interim conclusion
(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
(0:59:26) Outro
Papers/books that Russell refers to:
A. Roger Ekirch's book: “At Day's Close”
Thomas Wehr's research on bimodal or polymodal sleep:
"In short photoperiods, human sleep is biphasic" (Wehr 1992)
https://doi.org/10.1111/j.1365-2869.1992.tb00019.x
Russell's group - investigation on international populations, night owls were missing morning light
"Chronotype and environmental light exposure in a student population" (Porcheret et al. 2018)
https://doi.org/10.1080/07420528.2018.1482556
Charles Czeisler’s group - full-intensity kindle watching for 4 hours for 5 nights
"Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness" (Chang et al. 2014)
https://doi.org/10.1073/pnas.1418490112
Prior light exposure of 500-600 lux during the day abolished the suppressing-melatonin-effect
"The effects of prior light history on the suppression of melatonin by light in humans" (Hebert et al. 2002)
https://doi.org/10.1034%2Fj.1600-079x.2002.01885.x
Harvard group: aged humans show decreased sensitivity to light
"Decreased sensitivity to phase-delaying effects of moderate intensity light in older subjects" (Duffy et al. 2007)
https://doi.org/10.1016/j.neurobiolaging.2006.03.005
Christian Cajochen’s work on alertness, blue light is most important
"High Sensitivity of Human Melatonin, Alertness, Thermoregulation, and Heart Rate to Short Wavelength Light" (Cajochen et al. 2005)
https://pubmed.ncbi.nlm.nih.gov/15585546/
Arti Jagannath's work on jet lag:
SIK1 deletion in mice and jet lag:
"The CRTC1-SIK1 pathway regulates entrainment of the circadian clock" (Jagannath et al. 2013)
https://doi.org/10.1016/j.cell.2013.08.004
Recent review on SIK:
"The multiple roles of salt-inducible kinases in regulating physiology" (Jagganath et al. 2023)
https://doi.org/10.1152/physrev.00023.2022
How to contact Russell Foster:
Email: russell.foster@eye.ox.ac.uk
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.
More information about the Daylight Awareness Week: https://daylight.academy/daylight-awareness-week-2023/
Chapters:
(0:00:00) Intro & Daylight Awareness Week
(0:02:20) Topics of this episode series
(0:04:34) Introducing Russell Foster
(0:11:22) Evolution through daylight
(0:16:38) Physical properties of light
(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)
https://link.springer.com/chapter/10.1007/978-0-387-22628-6_17
J. N. Lythgoe's book: "The Ecology of Vision"
"Sensitivity and integration in a visual pathway for circadian entrainment in the hamster (Mesocricetus auratus)" (Nelson & Takahashi 1991)
https://doi.org/10.1113/jphysiol.1991.sp018660
"Phase-dependent shift of free-running human circadian rhythms in response to a single bright pulse" (Honma et al. 1987)
https://link.springer.com/article/10.1007/BF01945525
"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)
https://link.springer.com/article/10.1007/BF00198171
"Neural Reprogramming in Retinal Degeneration" (Marc et al. 2007)
https://doi.org/10.1167/iovs.07-0032
"Suprachiasmatic nucleus in the mouse: retinal innervation, intrinsic organization and efferent projections" (Abrahamson & Moore 2001)
https://doi.org/10.1016/S0006-8993(01)02890-6
Martin Ralph's tau mutant hamster, restore rhythms to the period of the donor:
"Transplanted suprachiasmatic nucleus determines circadian period" (Ralph et al. 1990)
https://www.science.org/doi/abs/10.1126/science.2305266
Peripheral clocks concept shown by Uli Schibler's group in fibroblasts:
"Resetting of Circadian Time in Peripheral Tissues by Glucocorticoid Signaling" (Balsalobre et al. 2000)
https://www.science.org/doi/10.1126/science.289.5488.2344
Josephine Arendt melatonin pioneer:
"Melatonin as a chronobiotic" (Arendt & Skene 2005)
https://doi.org/10.1016/j.smrv.2004.05.002
Contradictory evidence for the use of melatonin to facilitate the onset of sleep
Example meta-analysis article: "Effects of exogenous melatonin on sleep: a meta-analysis" (Brzezinski et al. 2005)
https://doi.org/10.1016/j.smrv.2004.06.004
Patients on beta-blockers produce less melatonin:
"Influence of beta-blockers on melatonin release" (Stoschitzky et al. 1999)
https://link.springer.com/article/10.1007/s002280050604
How to contact Russell Foster:
Email: russell.foster@eye.ox.ac.uk
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)
https://link.springer.com/article/10.1007/s40279-023-01822-3
Additional papers that Jorn refers to:
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)
https://pubmed.ncbi.nlm.nih.gov/25926415/
How to contact Jorn Trommelen:
Twitter: @JornTrommelen
Website: nutritiontactics.com
Instagram: @nutritiontactics
LinkedIn: https://www.linkedin.com/in/jorntrommelen/
Email: jorn.trommelen@maastrichtuniversity.nl
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)
https://link.springer.com/article/10.1007/s40279-023-01822-3
Additional papers that Jorn refers to:
Yves Boirie, guy who invented the cow model
First study about production of the labeled milk:
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)
https://pubmed.ncbi.nlm.nih.gov/34642762/
Jorn's review on this model:
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)
https://pubmed.ncbi.nlm.nih.gov/28855419/
How to contact Jorn Trommelen:
Twitter: @JornTrommelen
Website: nutritiontactics.com
Instagram: @nutritiontactics
LinkedIn: https://www.linkedin.com/in/jorntrommelen/
Email: jorn.trommelen@maastrichtuniversity.nl
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)
https://academic.oup.com/sleep/article/32/3/311/3741695
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)
https://www.jahonline.org/article/S1054-139X(14)00324-3/fulltext
Rods and cones also play a role for light suppression on melatonin etc.
S-cone contribution to the acute melatonin suppression response in humans (Brown et al. 2021)
https://onlinelibrary.wiley.com/doi/full/10.1111/jpi.12719
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)
https://www.pnas.org/doi/full/10.1073/pnas.1006749107
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)
https://doi.org/10.1161/01.CIR.93.7.1364
How to contact Frank Scheer:
LinkedIn: https://www.linkedin.com/in/frankscheer/
Email: FSCHEER@BWH.HARVARD.EDU
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)
https://www.science.org/doi/10.1126/sciadv.abg9910
Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity (Vujovic et al. 2022)
https://www.cell.com/cell-metabolism/pdfExtended/S1550-4131(22)00397-7
Additional papers that Frank and I refer to:
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
Adaptation of the melatonin rhythm in human subjects following night-shift work in Antarctica (Midwinter & Arendt 1991)
https://pubmed.ncbi.nlm.nih.gov/2027519/
Energy Expenditure and Changes in Body Composition During Submarine Deployment—An Observational Study “DasBoost 2-2017” (Rietjens et al. 2020)
https://www.mdpi.com/2072-6643/12/1/226
The Relationship between Working Night Shifts and Depression among Nurses: A Systematic Review and Meta-Analysis (Okechukwu et al. 2023)
https://pubmed.ncbi.nlm.nih.gov/37046864/
Circadian misalignment increases mood vulnerability in simulated shift work (Chellappa et al. 2020)
https://www.nature.com/articles/s41598-020-75245-9
Proof-of-principle demonstration of endogenous circadian system and circadian misalignment effects on human oral microbiota (Chellappa et al. 2022)
https://pubmed.ncbi.nlm.nih.gov/34861073/
Review articles on shift work and health risks:
Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes (Mason et al. 2020)
https://pubmed.ncbi.nlm.nih.gov/31915891/
Impact of Circadian Disruption on Cardiovascular Function and Disease (Chellappa et al. 2019)
https://pubmed.ncbi.nlm.nih.gov/31427142/
Health consequences of circadian disruption (Sletten et al. 2020)
https://academic.oup.com/sleep/article/43/1/zsz194/5699236?login=true
Effects of circadian disruption on the cardiometabolic system (Rüger & Scheer 2009)
https://link.springer.com/article/10.1007/s11154-009-9122-8
The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles (Scheer et al. 2020)
https://www.pnas.org/doi/abs/10.1073/pnas.2018486118
The two-process model of sleep regulation: Beginnings and outlook (Borbely 2022)
https://onlinelibrary.wiley.com/doi/full/10.1111/jsr.13598
Controlling for sleep as a factor in the negative effects of shift work, circadian misalignment is above and beyond sleep-disruptive effects:
Circadian Misalignment Augments Markers of Insulin Resistance and Inflammation, Independently of Sleep Loss (Leproult et al. 2014)
https://diabetesjournals.org/diabetes/article/63/6/1860/34298/Circadian-Misalignment-Augments-Markers-of-Insulin
Endogenous circadian system and circadian misalignment impact glucose tolerance via separate mechanisms in humans (Morris et al. 2015)
https://www.pnas.org/doi/abs/10.1073/pnas.1418955112
Adverse metabolic and cardiovascular consequences of circadian misalignment (Scheer et al. 2009)
https://www.pnas.org/doi/abs/10.1073/pnas.0808180106
Shift work studies in mice by Carolina Escobar:
Food Intake during the Normal Activity Phase Prevents Obesity and Circadian Desynchrony in a Rat Model of Night Work (Salgado-Delgado et al. 2010)
https://academic.oup.com/endo/article/151/3/1019/2456529
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)
https://www.nature.com/articles/ijo2012229
How to contact Frank Scheer:
LinkedIn: https://www.linkedin.com/in/frankscheer/
Email: FSCHEER@BWH.HARVARD.EDU
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)
https://physoc.onlinelibrary.wiley.com/doi/full/10.1113/JP278996
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)
https://link.springer.com/article/10.1007/s40279-019-01053-5
Studies on lowering pain after exercise through the cold:
Cold water immersion and recovery from strenuous exercise: a meta-analysis (Leeder et al. 2019)
https://paulogentil.com/pdf/Cold%20water%20immersion%20and%20recovery%20from%20strenuous%20exercise%20-%20a%20meta-analysis.pdf
Cold to maintain workload in sets:
Water Immersion Recovery for Athletes: Effect on Exercise Performance and Practical Recommendations (Versey et al. 2013)
https://link.springer.com/article/10.1007/s40279-013-0063-8
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)
https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP272881
Cold on the muscle clock in mice:
Time-of-Day Effects on Metabolic and Clock-Related Adjustments to Cold (Machado et al. 2018)
https://www.frontiersin.org/articles/10.3389/fendo.2018.00199/full
How to contact with Cas Fuchs:
Twitter: @27CJ
Email: cas.fuchs@maastrichtuniversity.nl
