Confirmed links between insomnia, microbiota, and inflammation?
A study has shed light on the links between gut microbiota, inflammation and insomnia, a very common sleep disorder that affects 10%-50% of adults worldwide. Further details below.
About this article
Insomnia is a condition that interferes with onset, maintenance, and quality of sleep. It is generally linked to genetic, hormonal, immune or psychosocial predispositions, and it can have a serious impact on daytime functioning.
Gut microbiota in the dock
The gut microbiota may be to blame, specifically via the gut-brain axis, which enables communication between bacteria in the digestive tract and those in the brain. Various studies in animals have shown sleep disturbances to be frequently associated with changes in the composition and function of the gut microbiota (dysbiosis). Conversely, the restoration of normal gut flora improves the quality of sleep. These interactions are thought to involve cytokines (inflammatory molecules produced by the immune system in response to certain gut bacteria), which could explain the inflammation observed in insomniacs.
Bacterial “signatures” of insomnia
These data mainly result from work carried out on animals. Seeking confirmation in humans, researchers analyzed and compared the gut microbiota and cytokine production of 96 adults, including 20 suffering from acute insomnia, 38 from chronic insomnia and 38 normal sleepers, who served as controls. The first finding was that insomniac patients showed higher levels of inflammatory cytokines than normal sleepers, and these levels appeared to increase with the severity of the disease. Their microbiota also showed a depletion of certain bacteria known to produce short-chain fatty acids (compounds with anti-inflammatory and health benefits). The researchers also identified bacterial “signatures” that reflect the quality of sleep and the severity of insomnia. These signatures made it possible to distinguish acute and chronic insomniacs from normal sleepers.
Overcoming insomnia thanks to the microbiota?
This study confirms that there are alterations to the gut microbiota in cases of insomnia, the severity of which may be linked to the presence or absence of certain bacterial groups. Any resulting inflammation is thought to depend on the duration of the (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232. ) . The microbiota may therefore be used to develop diagnostic or therapeutic tools that target this sleep disorder.
Yuanyuan Li, Bin Zhang, Ya Zhou et al. Gut microbiota changes and their relationship with inflammation in patients with acute and chronic insomnia. Nature and Science of Sleep. 2020; 12:895-905.