The constant communication and interplay between the gut, the brain and other systems in the body has the potential to influence and intersect with sleep, both directly and indirectly. In humans, disruption of the circadian (24 hour) clock is a common hallmark of the modern alteration in lifestyle and is especially evident in individuals engaged in chronic shift work or frequently flying across time zones and experiencing “jet lag.”
Our intestinal microbiota exhibit daily oscillations in composition and function and the gut microbiome appears to have its own daily rhythms that are deeply entwined with our own circadian rhythms and are capable of influencing and disrupting each other. Under normal circumstances our gut microbime rhythm supports our own circadian rhythms and induction of “jet lag” in both mice and humans results in microbial dysbiosis, which drives metabolic imbalances. This in part explains how shift work is associated with a wide range of diseases, including obesity, diabetes, cancer, cardiovascular disease, and susceptibility to infection. In studies, partial sleep deprivation alters the human gut microbiome and the altered microbiome composition appears to lead to adverse cognitive outcomes.
In animal studies, deliberate manipulation of intestinal flora causes changes in sleep behavior. Antibiotic-induced depletion of the gut microbiota reduces nocturnal sleep, and increases nighttime activity, probably via animals’ ability to diminish gut-derived bacterial somnogens. These studies suggest an emerging paradigm whereby a feedback loop exists between our daily rhythms and the microbiota with mutual cross-regulation of many functions within the body.
In a very recent study researchers reported that the gut microbiome diversity (which is what I talk about all the time) positively correlated with sleep efficiency and total sleep time, and negatively correlated with wake after sleep onset, which suggests that gut microbiome could be involved in promoting better sleep. Additionally, increased microbiome diversity was also associated with cognitive flexibility and abstract thinking, which were assessed through cognition and emotion test battery.
(Gut microbiome diversity is associated with sleep physiology in humans Robert P. Smith, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0222394