Research Reveals Two-Way Link Between Gut and Sleep Health

8.19.2025 0 comments

Author: Trisha Houghton, CNS, ASIST

A new study published in General Psychiatry on August 12th, 2025, suggests a bidirectional relationship between the gut microbiome and sleep insomnia – indicating that our gut bacteria can influence sleep health – and vice versa. This research was conducted by using large-scale genetics datasets from reliable sources and a Mendelian randomisation (MR) analysis.

This approach allowed the scientists to provide early evidence that specific groups of bacteria can either increase or decrease the risk of insomnia.

Read the full study here: https://gpsych.bmj.com/content/38/4/e101855

What the Study Found

The study, mostly led by Chinese scientists, uncovered several notable associations in both directions – gut bacteria affecting sleep health, and insomnia influencing the composition of people’s gut microbiomes.

• 14 species of gut bacteria were linked to higher likelihood of experiencing sleep insomnia – but 8 other bacterial groups appeared to have protective properties, lowering the risk for sleep issues.
• However, after a statistical correction for false discovery, only one causal association between the Clostridium innocuum pathogen and insomnia remained significant.
• Scientists also discovered a bidirectional relationship between the genus Odoribacter and insomnia in multiple independent datasets.

Together, these findings point us to a complex, dynamic relationship between our gut and sleep health – showing that it’s not just one that may impact the other.

Who Was Studied

To conduct their detailed analysis, the scientists relied on two major genetic datasets:

• The insomnia-related genetic data came from 386,533 participants in a large genome-wide association study (GWAS) that has been published in 2019.
• Gut microbiome profiles were drawn from two sources – 18,340 datasets from the MiBioGen alliance, and 8,208 datasets from the Dutch Microbiome Project.
• All the information came from participants of European ancestry, which the study authors see as a potential limitation.

Thanks to the large-scale approach that looked at thousands of datasets, the scientists were able to reduce the risk for bias, further strengthening the evidence for a causal microbiome-sleep relationship.

Why This Study Matters

This 2025 study comes in at the right time not just because of the medical world’s growing interest in the gut-brain axis.

With insomnia being the most common sleep disorder worldwide – often linked to chronic pain, mood disorders, and hormonal imbalances – these findings shed new light on how we can promote our quality of sleep.

The gut microbiome, which has already been known for its role in digestion and immunity, now appears to be connected to sleep regulation in a bidirectional way. This simple, yet profound conclusion means that addressing our gut health may soon become a personalized strategy for improving sleep.

At the same time, this may signal that managing sleep could contribute to a healthier gut, better digestion, and more robust immune defenses.

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How Experts Reacted to the Study

Only a few days after the release of the article,two sleep specialists reacted to the study in Medscape Medical News.

“I have a difficult time understanding the authors’ interpretation that these findings demonstrate bidirectional causality, or more specifically that gut biome flora causes insomnia,” skeptically said Dr. Charlene Gamaldo, a Professor of Neurology at Johns Hopkins School of Medicine. “For me the question is whether these types of associations like stress, environmental triggers, etc, serve as upstream triggers to cause both insomnia and gut biome changes simultaneously or in succession?”

Dr. Gamaldo’s interesting point of view suggests that the relationship may not be direct – but rather influenced by other underlying factors such as stress and lifestyle, which could drive changes in both sleep and gut health at the same time.

Another independent expert, Dr. John Saito, who’s a pulmonologist and a spokesperson for the American Academy of Sleep Medicine, stated that “While there is general recognition that disruption of gut microbiome may have central nervous system consequences, including alteration in sleep health, more research is needed before it would be feasible to diagnose or treat insomnia by focusing on changes in the gut microbiota.”

Dr. Saito’s comment seems to be in line with Dr. Gamaldo’s opinion, since both experts agree that the study’s findings, while intriguing, are not strong enough to support immediate clinical applications.

What Future Research May Focus On

The researchers realize that while this study is a strong starting point, it doesn’t show the complete picture of how our gut impacts sleep, and vice versa. Further studies may focus on more diverse populations and lifestyle interventions to shape new approaches to insomnia treatment.

As stated at the end of the paper, “Randomised controlled trials assessing microbiome-targeted interventions, such as probiotics, prebiotics or faecal microbiota transplantation, would offer critical translational insights into therapeutic modulation of the gut–brain axis in insomnia.”

The bidirectional link between gut health and sleep is an emerging area of science, and this study adds an important piece of the puzzle. In the near future, we may find more holistic solutions that incorporate sleep hygiene, behavioral therapy, and gut-focused therapies for sustainable and effective health outcomes.

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