Microbes That Keep You Awake or Help You Rest

Gut bacteria show a two-way connection with insomnia, potentially influencing and being influenced by the sleep disorder.

Fourteen groups of gut bacteria have been found to either increase or decrease the risk of insomnia, and the sleep disorder itself appears to alter the abundance of certain bacterial populations, according to findings published in the open-access journal General Psychiatry.
These observations suggest a two-way link between specific gut microbes and insomnia, where some bacteria seem to either promote or protect against the sleep issue, and insomnia may, in turn, reshape the gut microbiome (1^✔ ✔Trusted Source
Investigating bidirectional causal relationships between gut microbiota and insomnia

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Use of Genetic Data to Explore the Connection

Although earlier studies hinted at gut–sleep connections, the exact role of individual microbes was unclear. Since insomnia affects 10–20% of people worldwide, researchers sought more definitive evidence by applying Mendelian randomization—a method that uses genetic variants as natural experiments to test causal relationships.

Extensive Genetic and Microbiome Datasets Used

The study drew on genetic data from 386,533 individuals diagnosed with insomnia, sourced from a prior genome-wide association study. For gut microbiome information, data were used from two large databases: 18,340 participants from the MiBioGen alliance and 8,208 from the Dutch Microbiome Project, focusing on 71 bacterial groups that overlapped between the datasets.

Analysis identified significant associations between particular gut bacteria and insomnia. Fourteen types of bacteria were linked with a 1 to 4 percent higher chance of developing insomnia, while eight types were associated with a 1 to 3 percent lower risk.

Insomnia Alters Gut Bacteria Abundance

Interestingly, insomnia was also found to change the balance of gut bacteria. The condition was associated with a 43 to 79 percent reduction in seven bacterial groups and an increase ranging from 65 percent to over fourfold in twelve other groups.

One group of bacteria, known as Odoribacter, was notably and consistently associated with insomnia risk, suggesting its possible involvement in sleep regulation or disturbance.

Robust Evidence Without Genetic Overlap

No evidence of pleiotropy, where a single gene affects multiple traits, was found in the analysis, which reinforces the validity of the results and points to a likely causal relationship between insomnia and gut microbiota.

These findings align with many earlier studies that propose a dynamic relationship between sleep disorders and gut bacteria. However, the researchers caution that certain limitations must be considered.

Population and Lifestyle Considerations

All participants in the analysis were of European descent, which means the findings may not apply universally, since gut microbiome compositions differ by ethnicity and geographic location. Additionally, external influences like diet, lifestyle, and gene-environment interactions were not accounted for in the analysis.

“Overall, the intertwined effects of insomnia on gut microbiota, and vice versa, represent a complex bidirectional relationship involving immune regulation, inflammatory response, release of neurotransmitters, and other molecular and cellular pathways,” the researchers explained.

Potential for Microbiome-Based Therapies

In their conclusion, the authors suggest that their work offers early evidence for a potential causal connection between gut microbiota and insomnia, opening new avenues for treatment options centered around the microbiome.

Possible future interventions could involve the use of probiotics, prebiotics, or even fecal microbiota transplantation to help manage or reduce symptoms of insomnia.

To sum up, the study presents compelling evidence of a bidirectional relationship between gut bacteria and insomnia, indicating that specific microbes may influence sleep quality and that insomnia can, in turn, reshape the gut microbiome.

Reference:

1. Investigating bidirectional causal relationships between gut microbiota and insomnia – (https://gpsych.bmj.com/content/38/4/e101855)

Source-Medindia