Fecal Transplant Tied to Improved Sleep in Chronic Insomnia

A treatment protocol using fecal microbiota transplantation (FMT) improved objective sleep measures in adults with chronic insomnia disorder.Results of a small, randomized, double-blind, placebo-controlled trial showed that participants who received the FMT-based protocol had significantly greater improvements in sleep efficiency and reductions in wake after sleep onset than those who received a placebo.Patient-reported sleep quality also improved and was sustained for 2-6 months after treatment in the FMT group. Treatment-related adverse events (AEs) were mild and self-limited, and no serious AEs were reported.“The main message is that targeting the gut microbiota may offer a promising new therapeutic direction for chronic insomnia,” said co-investigator Yanping Bao, PhD, professor at the National Institute on Drug Dependence at Peking University in Beijing, China.“The study also strengthens our understanding of the gut-brain axis as an important regulator of human sleep,” Bao told Medscape Medical News.However, she cautioned that larger studies are needed before FMT can be considered a routine treatment for chronic insomnia.The study was published online on July 22 in the Journal of Internal Medicine.Restructuring Gut Ecosystems“FMT can restructure disrupted gut microbial ecosystems and has been used across several clinical indications,” the investigators wrote. Some of the conditions that FMT have been assessed for in previous studies include Parkinson’s disease and depression.Bao noted that her team has been investigating the relationship between sleep and the gut microbiome for several years. In earlier preclinical studies, they transferred fecal microbiota from patients with insomnia into germ-free mice, inducing insomnia-like phenotypes.“This finding suggested that alterations in the gut microbiota might contribute to sleep disturbances rather than simply result from them,” said Bao.They then moved to a rigorously designed clinical trial to determine whether directly modifying the gut microbiota could produce measurable improvements in sleep among patients with chronic insomnia.The study included 80 patients aged 18-60 years with chronic insomnia disorder at seven hospital in China and followed them through July 2025.Half of the participants were randomly assigned to receive a short-course pretreatment with antibiotics followed by capsules containing fecal microbiota from carefully screened healthy donors (mean age, 40 years; 60% women), whereas the other half received placebo capsules without the antibiotic pretreatment (mean age, 46 years; 73% women).Each group was further divided for exploratory analysis, with 20 in each also receiving synbiotic supplementation and the other 20 in each receiving additional placebo.The primary outcome was sleep efficiency at 1 month post-treatment, as measured by overnight polysomnography. Secondary measures included patient-reported sleep outcomes and safety.Clinical Evidence?Results showed that the main FMT group had significantly better sleep efficiency at 1 month than the main placebo group (adjusted between-group difference, 13.9 percentage points; P = .003). There were no significant differences in sleep efficiency between the subgroups that did and did not receive synbiotic supplementation.The FMT group also had a greater reduction in wake after sleep onset (adjusted between-group difference, -41.5 minutes; P = .001). Although they also had more total sleep time (difference, 48.6 minutes; P = .03), this difference did not remain significant after multiple testing.Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI) scores showed sustained improvement from 2 to 6 months. The adjusted between-group difference for the FMT group on the ISI was -4.48 (P < .001) at month 2 and -2.49 (P = .04) at month 6. Adjusted between-group differences for the FMT group on the PSQI were -4.39 (P < .001) and -2.22 (P = .008) at months 2 and 6, respectively.In addition, the FMT protocol “increased microbial richness and diversity and altered community structure,” the investigators reported.Treatment-related AEs occurred in 7.5% of the FMT group members. No serious AEs, treatment-related infections, or hospitalizations of any type occurred in either study group.“Our findings provide clinical evidence that the gut microbiota may be a modifiable component of the biological systems regulating human sleep,” Bao said.However, she added that the study was primarily designed to evaluate clinical efficacy, not to establish precise biological mechanisms. “Further research is therefore needed to identify the specific microorganisms, metabolites, and host signaling pathways responsible for the observed effects,” Bao said.The American Academy of Sleep Medicine (AASM) Weighs InJohn Saito, MD, a spokesperson for the AASM and board certified in pediatric pulmonology and sleep medicine at Rady Children’s Health in Orange, California, told Medscape Medical News that “it’s fascinating” that the field of medicine is starting to recognize that gut bacteria can have a strong effect on the body in several different ways.“When people get fecal matter transplant, it can affect their metabolism, and this study narrowed down what its effect might be in sleep,” said Saito, who was not involved in the research.He added that the findings also help advance “at least the clinical observation” that changing gut microbiota may bring about change in insomnia outcomes and he would welcome more research into this area.“As a clinician and a spokesperson for the AASM in the US, I’d say that one study isn’t going to be convincing to tell us that we need to change what we do. But it does point us in the direction of being more mindful of what we eat and how it can influence our systems,” Saito said.The study was funded by the Brain Science and Brain-Inspired Intelligence Technology major project and by the National Natural Science Foundation of China. The investigators and Saito reported no relevant financial disclosures.