The Sleep Gut Connection Part 2: Circadian Rhythms

A growing number of studies now suggest that the vast and diverse microbial ecosystem of the gut has its own daily rhythms. These microbiome rhythms appear to be deeply entwined with circadian rhythms, the 24 hour biological rhythms that regulate sleep and wake cycles in addition to many important physiological processes. Research suggests that both circadian and microbial rhythms are capable of influencing and disrupting the other, with consequences for both health and sleep.

According to research, the rhythms of gut microbes are affected by what and when we eat. A study using mice found that when they ate a healthy diet, they generated more beneficial gut microbes, and that the collective activity of microbial life in the gut followed a daily — or diurnal — rhythm. That rhythm in turn supported circadian rhythms in the animal. Mice that were fed a high-fat, stereotypically “Western” diet, on the other hand, produced less optimal microbial life. The gut microbes of these mice did not adhere to a daily rhythm themselves, and also sent signals that disrupted circadian rhythms. These mice gained weight and became obese, while the mice that ate healthfully did not.

Scientists bred a third group of mice without any gut microbes at all. Because they lacked a gut microbiome, there were no bacteria to send signals to the rest of their bodies. Circadian disruption occurred in these mice, but they did not gain weight or suffer metabolic disruption, even when fed the high-fat diet. This suggests a couple of important conclusions. First, microbial activity is key to normal circadian function and, therefore to sleep. Second, that the microbiome is a key player along with diet in the regulation of weight and metabolism.

Research in humans has returned similar results. The human microbiome appears to follow daily rhythms influenced by timing of eating and the types of foods consumed, and to exert effects over circadian rhythms. Research has also found that the relationship between these different biological rhythms works both ways. Scientists have discovered that disruptions to circadian rhythms — the kind that occurs through jet lag, whether through actual travel or from “social” jet lag — disrupts microbial rhythms and the health of the microbial ecosystem. People who experience these changes to microbial rhythms as a result of circadian disruption suffer metabolic imbalance, glucose intolerance, and weight gain, according to research.

We’ve known for some time about the relationship of sleep, circadian rhythms, and metabolic health. Disrupted sleep and misaligned circadian rhythms have been strongly tied to higher rates of obesity, and to metabolic disorders including type 2 diabetes. This emerging knowledge of the microbiome and its relationship to circadian function may in time deliver to us a deeper understanding of how health is influenced by sleep and circadian activity.

Michael J. Breus, Ph.D., is a Clinical Psychologist and Diplomate of the American Board of Sleep Medicine as well as a Fellow of The American Academy of Sleep Medicine. He is one of only 168 psychologists in the world with his credentials and specialty in Sleep Disorders. Dr. Breus is the author of The Power of When, The Sleep Doctor’s Diet Plan, and Beauty Sleep. Dr. Breus is on uBiome’s scientific advisory board and on the clinical advisory board of The Dr. Oz Show and has appeared regularly on the show (39 times in 8 seasons). You can connect with Dr. Breus at www.thesleepdoctor.com or on Facebook @thesleepdoctor or Twitter @thesleepdoctor.

Reference list:

Akerstedt, T. (2006). Psychosocial stress and sleep. Scandinavian Journal of Work, Environment, & Health. 32(6): 493-501. http://www.jstor.org/stable/40967601.

Anderson, G. and Maes, M. (2015). The gut-brain axis: role of melatonin in linking psychiatric, inflammatory, and neurodegenerative conditions. Advances in Integrative Medicine. 2(1): 31-7. doi:10.1016/j.aimed.2014.12.007

Azvolinsky, A. (2015-4-16). Gut microbes influence circadian clock. The Scientist. http://www.the-scientist.com/?articles.view/articleNo/42715/title/Gut-Microbes-Influence-Circadian-Clock/

Bischoff, S.C. (2011). Gut health: a new objective in medicine? BMC Med, 9:24. doi: 10.1186/1741-7015-9-24

Brain Basics: Understanding Sleep. (2014-7-25). National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm

Bush, B. and Hudson, T. (2010). The role of cortisol in sleep. Natural Medicine Journal. 2:6. http://www.naturalmedicinejournal.com/journal/2010-06/role-cortisol-sleep

Carpenter, S. (2012-09). That gut feeling. Monitor on Psychology. 43:8. http://www.apa.org/monitor/2012/09/gut-feeling.aspx

Chichlowski, M. and Rudolph, C. (2015) Visceral pain and gastrointestinal microbiome. Journal of Neurogastroenterology and Motility. 21(2): 172-181. http://dx.doi.org/10.5056/jnm15025

Circadian Rhythm Fact Sheet. (2005-10-01). National Institute for General Medical Sciences. https://www.nigms.nih.gov/Education/Pages/Factsheet_CircadianRhythms.aspx

Forsythe, P. et al. (2010). Mood and gut feelings. Brain, Behavior, and Immunity. 24(1): 9-16. doi:10.1016/j.bbi.2009.05.058.

Foster, J.A. and McVey Neufeld, K A. (2013). Gut-brain axis: how the microbiome influences anxiety and depression. Trends in Neurosciences. 36(5): 305-312. doi:10.1016/j.tins.2013.01.005

Galland, L. (2014). The gut microbe and the brain. Journal of Medicinal Food. 17(12): 1261-72. doi: 10.1089/jmf.2014.7000.

Huang, W. et al. (2011). Circadian rhythms, sleep, and metabolism. Journal of Clinical Investigation. 121(6): 2133-41. doi: 10.1172/JCI46043.

The Human Microbiome. http://learn.genetics.utah.edu/content/microbiome/

Leone, V et al. (2015). Effects of diurnal variation of gut microbes and high-fat feeding on host circadian clock function and metabolism. Cell Host & Microbe, doi:10.1016/j.chom.2015.03.006.

Liang, X. et al. (2015). Rhythmicity of the intestinal microbiota is regulated by gender and the host circadian clock. Proceedings of the National Academy of Sciences. 201501305 DOI: 10.1073/pnas.1501305112

Moloney, R.D. and Desbonnet, L. et al. (2014) The microbiome: stress, health and disease. Mammalian Genome. 25(1): 49-74. doi: 10.1007/s00335-013-9488-5

Montel-Castro, A.J. et al. (2013). The microbiota-gut-brain axis: neurobehavioral correlates, health and sociality. Frontiers in Integrative Neuroscience. 7:70. doi:  10.3389/fnint.2013.00070

Moreno-Indias, I. et al (2015). Intermittent hypoxia alters gut microbiota diversity in a mouse model of sleep apnoea. European Respiratory Journal. 45(4): 1055-65. doi: 10.1183/09031936.00184314

Mukherjee, S. and Maitra, S.K. (2015). Gut melatonin in vertabrates: chronobiology and physiology. Frontiers in Endocrinology. 6:112 http://dx.doi.org/10.3389/fendo.2015.00112.

Pain and Sleep. National Sleep Foundation. https://sleepfoundation.org/sleep-disorders-problems/pain-and-sleep

Pollan, M. (2013, May). Some of my best friends are germs. New York Times Magazine. http://www.nytimes.com/2013/05/19/magazine/say-hello-to-the-100-trillion-bacteria-that-make-up-your-microbiome.html?_r=1

Schwartz, J.R.L. and Roth, T. (2008). Neurophysiology of sleep and wakefulness: basic science and clinical implications. Current Neuropharmacology. 6:4, pp. 367-378. doi: 10.2174/157015908787386050

Taylor, D. et al. (2005). Epidemiology of insomnia, depression and anxiety. SLEEP 28(11): 1457-1464. http://www.journalsleep.org/Articles/281117.pdf

Thaiss, C.A., et al. (2014) Transkingdom control of microbiota diurnal oscillation promotes metabolic homeostasis. Cell, 159:33, p514-529. doi: http://dx.doi.org/10.1016/j.cell.2014.09.048

Voight, R.M. et al. (2014) Circadian disorganization alters intestinal microbiota. PLoS ONE 9(5): e97500. doi: 10.1371/journal.pone.0097500

Wood, M. (2015-5-13). The microbiome and the midnight snack: how gut microbes influence the body’s clock. Science Life. http://sciencelife.uchospitals.edu/2015/05/13/the-microbiome-and-the-midnight-snack-how-gut-microbes-influence-the-bodys-clock/