Fecal Transplant Improves Sleep Efficiency in Adults with Chronic Insomnia, Trial Finds

How the Fecal Transplant Sleep Trial Was Conducted

The multicenter, randomized, double-blind, placebo-controlled trial enrolled 80 adult participants in China diagnosed with chronic insomnia disorder, according to study authors Zhe Wang of the Institute of Brain Science and Brain-Inspired Research at Shandong First Medical University in Jinan and Yanping Bao of the National Institute on Drug Dependence at Peking University in Beijing. Researchers first administered a short course of antibiotics to reduce existing gut bacteria in all participants. Following the pretreatment, 40 participants received donor microbiota capsules while 40 received placebo capsules without antibiotic pretreatment.

Healthy donors with no sleep disorders or psychiatric symptoms provided the material for the treatment capsules. One month post-treatment, participants underwent evaluation in a sleep laboratory. Investigators tracked how long participants slept, how frequently they woke up, and sleep efficiency—defined as the percentage of time someone spent asleep. Additional randomization within the groups tested synbiotic supplementation, though researchers observed no meaningful differences in sleep efficiency associated with synbiotic assignment.

Measured Improvements in Sleep Continuity

Participants who received the fecal transplant capsules saw their sleep efficiency jump from approximately 79 percent before treatment to 93 percent one month later. In contrast, the placebo group showed minimal change, moving from 85 percent to 87 percent. Individuals in the FMT group also spent about 42 fewer minutes awake after falling asleep compared to those taking the dummy pills.

According to self-reported questionnaires gathered during the trial, these therapeutic gains persisted for up to six months. Teng Gao from the Peking University Institute of Mental Health in Beijing and colleagues also noted sustained improvements in scores on the Insomnia Severity Index and the Pittsburgh Sleep Quality Index between two and six months post-intervention. Stool analysis confirmed that microbial richness and diversity increased, and community structure altered following the intervention.

Safety and Tolerability of the Intervention

The FMT-based treatment protocol was generally well tolerated by participants. Researchers recorded only mild, self-limited adverse events, with no serious adverse events reported during the study period. Posttreatment changes in beta-diversity were similar in both responders and nonresponders, though individuals in those two categories exhibited different baseline microbiota compositions prior to receiving the capsules.

“Targeting the gut microbiota may offer a promising new therapeutic strategy for chronic insomnia disorder,” coauthor Yanping Bao said in a statement reported by HealthDay News. “This work also strengthens our understanding of the gut-brain axis as an important regulator of human sleep.”

Expert Perspective and Study Limitations

Erica Jansen, an assistant professor of nutritional sciences at the University of Michigan in Ann Arbor who studies the health impacts of diet and sleep and was not involved in the trial, explained that the interaction is biologically plausible. “We know that there is cross-talk between the gut and the brain, so it makes sense that having a healthier gut microbiome could be connected to overall brain function and to sleep,” Jansen said.

Study authors Wang and Bao emphasized several limitations that require caution before clinical translation. The trial relied on a modest sample size of 80 participants, meaning the findings must be replicated in larger and more diverse populations. Furthermore, researchers have not yet identified which specific microorganisms or microbial functions generated the benefits, whether different donor preparations would have similar effects, or how long the improvements may persist. The trial was structured to evaluate clinical efficacy rather than to establish the exact biological mechanism.