New research from China suggests that the microbes in your gut could be influencing whether you sleep well—or at all. Remarkably, the reverse also appears to be true: your sleeping patterns may directly impact the health of your gut. While previous studies hinted at a link between sleep and gut health, a recent analysis published in General Psychiatry indicates that this relationship could be causal. In other words, your sleep may shape your gut microbiome, and the microbiome may, in turn, influence your sleep.
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Dr Shi Shangyun, the study’s lead author from the Affiliated Brain Hospital of Nanjing Medical University, told BBC Science Focus that the findings have the potential to “reshape understanding of insomnia and inspire interest in microbiome-based research and interventions.”
Looking ahead, insomnia treatments could target the gut. Options might include probiotics—such as yoghurt or sauerkraut—prebiotics, or even faecal transplants, the researchers suggest. “The gut microbiome may also serve as a biomarker to track treatment effectiveness, enabling more personalised care,” added Shangyun.
The team employed Mendelian randomisation analysis, a statistical method that uses genetic data to infer cause and effect, to explore the relationship between insomnia and gut microbes. They first identified genes linked to insomnia and then analysed whether individuals carrying those genes were more likely to host particular gut bacteria. The reverse was also examined: whether certain gut microbes increased or reduced the likelihood of insomnia.
The study drew upon genetic data from 387,000 people with insomnia and gut microbiome data from 26,500 participants, all of European descent. This means that findings may not necessarily apply to other populations.
Analysis suggested that 41 types of gut bacteria could partially cause insomnia. Of these, 14 bacterial groups were associated with a higher likelihood of insomnia, while eight groups appeared linked with a lower risk. Conversely, insomnia was connected to a reduction of between 43–79 per cent in seven bacterial groups, and a 65 per cent likelihood that 12 other groups were four times more abundant. One bacterium, Odoribacter, stood out for its strong association with insomnia risk. Typically linked to better gut health, its role in sleep disruption highlights the complex interplay between microbes and the body.
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Ultimately, the study revealed a vicious cycle: certain gut bacteria may provoke insomnia, yet poor sleep may simultaneously reshape the gut microbiome. Shangyun cautioned that more research is required before doctors can prescribe gut-targeted strategies to help patients achieve better sleep.
