Gut microbiota alterations in sleep disturbances: A systematic review and meta-analysis.

Emerging evidence links gut dysbiosis to sleep disturbances, yet a comprehensive synthesis defining specific and shared microbiota alterations across sleep disorders is lacking. In this systematic review and meta-analysis, we searched PubMed, Cochrane Library, Web of Science, Embase, and PsycINFO for articles published up to Sep 20, 2025. Data from 53 studies were included in the quantitative analysis. The alpha diversity was decreased in individuals with sleep disturbances compared to controls (Shannon index standardized mean difference [SMD] = -0.24, 95% CI: -0.34 to -0.15; Chao1 index SMD = -0.29, 95% CI: -0.40 to -0.17; observed species SMD = -0.27, 95% CI: -0.40 to -0.14). However, this finding was sensitive to publication bias: after trim-and-fill adjustment, the association with the Shannon index became non-significant. Significant beta diversity shifts were observed for rapid eye movement sleep behavior disorder (RBD) and abnormal sleep duration. While evidence for disease-specific microbial alteration was limited, a shared pattern of microbiota alteration was suggested across insomnia, obstructive sleep apnea, and RBD, characterized by reduced relative abundance of anti-inflammatory, butyrate-producing bacteria (e.g., Faecalibacterium, Lachnospira) and increased abundance of Collinsella. In summary, this meta-analysis suggests a shared gut microbiota alteration in sleep disorders, though these findings are exploratory and should be interpreted cautiously given the limited confounding control.