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