Sleep, Inflammation, and the Gut Microbiome

Sleep, Inflammation, and the Gut Microbiome

Short periods of sleep deprivation affect millions of people worldwide and in susceptible individuals is known to contribute to a decrease in cognitive performance, increased inflammation, and dysbiosis in the gut.

If sleep deficiency is chronic, this can result in several health problems. Chronic short sleep duration has been shown to lead to a state of chronic systemic immune system activation, which has been associated with a variety of non-communicable diseases. Metabolic diseases such as metabolic syndrome, pre-diabetes, or type II diabetes, as well as cardiovascular diseases, and even some mental illnesses such as anxiety and depression show evidence of chronic immune system as part of their underlying pathophysiology. As a history compromised sleep loss is often present in individuals with such conditions, it is important to investigate the link between the two. Such investigations may identify sleep as a target for treatment and prevention.

Several studies have aimed at investigating the link between sleep deprivation and chronic inflammation by looking at the gut microbiome. Converging evidence implicates the gut microbiome as an important player in the pathophysiology of chronic inflammation and resulting chronic diseases. We know that these mechanisms work through changes of intestinal barrier permeability which cause heightened immune activation and the corresponding secretion of inflammatory markers as well as stress hormones through activation of the HPA axis. A study investigating the link between gut disturbances and sleep deficiency showed that sleep restriction caused both structural and functional changes in the gut microbiome. Other studies have confirmed this finding. Therefore, it makes sense to suggest that microbial dysbiosis caused by sleep deprivation may be an underlying component of the inflammatory response which occurs so commonly in sleep deprived individuals. Another study highlights this link by demonstrating that sleep deprivation induced gut dysbiosis as well as heightened inflammation in mice. Convergingly, these studies suggest that sleep disturbance, gut dysbiosis, and chronic inflammation are directly linked, hence opening up the field for more targeted treatment of inflammation-related disease by incorporating sleep and other lifestyle factors known to affect the brain-gut axis.

Another important thing to highlight regarding this topic is the link between the gut microbiome and the body’s circadian rhythm. This connection has been well researched in recent years and is known to play a critical role in health and longevity. The body’s circadian rhythm is a diurnal cycle of oscillatory fluctuations repeating every 24 hours and is heavily affected by two environmental factors, namely the light/dark cycle and the time of food ingestion. Fluctuations in gut microbial abundance and activity have been observed in tune with the body’s circadian rhythm. Furthermore, time restricted eating and nightly periods of fasting of a minimum of 12 hours have been shown to positively affect metabolism, body weight, and a heightened relative abundance of health-supporting bacteria in the gut. The connection between gut, brain, and the immune system involves many different layers and complex networks, suggesting that sleep deficiency is very likely to cause inflammation through the gut-brain-microbiome system. More research on the exact underlying mechanisms of how sleep deprivation causes inflammation in brain and body is needed to confirm and expand the current understanding of this topic.

However, one can still take advantage of this knowledge and reduce their body’s inflammatory state by making sure to maintain or achieve proper sleep hygiene. This would involve getting enough bright light exposure during the day, adopting a time-restricted eating schedule where one eats their meals around the same time every day, as well as avoiding bright light exposure and stress at night. If sleep deprivation is stress-related, another great habit to incorporate would be a daily meditation practice or other mindfulness-based interventions. These practices are known to activate the parasympathetic nervous system and allow the body and mind to get into a restful state which may help facilitate getting good sleep at night.

Jill Horn is an international student from Switzerland on a pre-med track, currently majoring in Neuroscience at UCLA.