The gut–sleep connection

We tend to think of sleep as a function of the brain, a product of hormones, stress, and routine. But scientists are increasingly finding that one of the biggest regulators of our sleep may live in an unexpected place: the gut.

There is a striking link between gut bacteria and sleep quality (Peking University Sixth Hospital). The research shows that the composition and balance of the gut microbiome actively influence the body’s sleep–wake cycles and that microbial imbalances could contribute to conditions such as insomnia, sleep apnoea, and other sleep disorders.

Microbes that talk to the brain

According to the study, the gut and brain maintain constant communication through three main pathways: the vagus nerve, the immune system, and metabolic signalling. In this complex dialogue, gut microbes produce active compounds such as short-chain fatty acids (SCFAs), particularly butyrate, which help reduce inflammation and promote better sleep. Other bacterial metabolites also play a key role in producing serotonin and melatonin, the hormones responsible for regulating mood and circadian rhythms.

The role of bacteria

Specific bacterial strains, like Lactobacillus and Bifidobacterium, were found to stimulate the production of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter that calms the nervous system and helps the body prepare for rest. When these beneficial bacteria decline, as observed in people with chronic insomnia or sleep aponia, the gut’s microbial diversity drops. Similar microbial patterns have been found in people with disrupted circadian rhythms, such as night-shift workers, suggesting that modern lifestyle habits may be reshaping the microbiome and our sleep in subtle but significant ways.

A new biomarker for brain health

Perhaps most strikingly, the study found that the same microbial imbalances appear in patients with neurodegenerative diseases like Parkinson’s, which are often accompanied by sleep disorders. This suggests that gut bacteria could serve as an early biomarker for diagnosing and understanding such conditions. As researchers continue to explore the gut–brain axis, one thing is becoming clear: the path to a good night’s sleep might just begin in the stomach.