The Sleep Gut Connection Part 1: Imbalances

Scientists investigating the relationship between sleep and the microbiome are increasingly finding a dynamic connection between gut health and brain health. The microbial ecosystem may affect sleep and sleep-related physiological functions in a variety of ways, including altering the body’s sleep-wake cycle and affecting the hormones that regulate sleep and wakefulness. The quality of our sleep, in turn, may affect the health and diversity of our microbiome.

There’s constant interplay between the gut and the brain, which means that a disturbance in either can influence sleep. The intestinal microbiome actually promotes the release of many of the neurotransmitters — including dopamine, serotonin, and GABA — that help to regulate mood and promote sleep. Studies show a strong connection between imbalance of gut microbes and stress, anxiety, and depression, which in turn can trigger or exacerbate sleep disruptions. Research also links gut health to pain perception. An unhealthy microbiome appears to increase sensitivity to visceral pain, which then can make falling asleep and staying asleep much more difficult.

Just as an imbalanced gut can affect sleep, unhealthy sleep patterns can disrupt the microbiome, as in the common sleep disorder, obstructive sleep apnea. In one study, scientists put mice through a pattern of disrupted breathing that mimicked the effects of OSA. They found that the mice that lived with periods of OSA-like breathing for six weeks showed significant changes to the diversity and makeup of their microbiota.

Gut health also has a significant connection to hormones that affect sleep. Melatonin, the “darkness hormone”, is essential to sleep and a healthy sleep-wake cycle. Melatonin is actually produced in the gut as well as the brain, and evidence suggests intestinal melatonin may operate on a different cyclical rhythm than the pineal melatonin generated in the brain.

Additionally, cortisol is critical to the sleep-wake cycle. This hormone is central to the body’s stress and inflammatory response, and exerts an effect on gut permeability and microbial diversity. Rising levels of cortisol very early in the day help to promote alertness, focus and energy. Changes to cortisol that occur within the gut-brain axis are likely to have an effect on sleep.

Put very simply: our gut affects how well we sleep, and sleep affects the health of our gut. When you improve one, you improve both, which makes for a much healthier – and better rested – you.

Sweet dreams!


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 or on Facebook: @thesleepdoctor, or Twitter @thesleepdoctor.


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