Oral microbiota diversity and compositional shifts in relation to sleep quality: a cross-sectional study in Beijing adults

Background Accumulating evidence indicates that the oral microbiome may modulate sleep homeostasis via the oral–gut–brain axis, yet population-based epidemiological data from Asian cohorts remain scarce. This study aimed to quantify the associations of oral microbial diversity and community composition with subjective sleep quality, and identify taxonomic biomarkers linked to sleep disturbances among urban Chinese adults. Methods A cross-sectional survey was conducted recruiting 73 adults aged 20–60 years in Beijing between April and July 2024. Salivary microbiota was profiled via 16S rRNA V3–V4 high-throughput sequencing. Sleep quality was evaluated using the validated Chinese version of the Pittsburgh Sleep Quality Index (PSQI). Participants were stratified into a high sleep quality group (HSQ, PSQI ≤ 5, n = 30) and a low sleep quality group (LSQ, PSQI > 5, n = 43). Alpha diversity (Shannon index) and beta diversity (Bray–Curtis, unweighted UniFrac distances) were compared between groups, while differential taxa were screened using linear discriminant analysis effect size (LEfSe) with a linear discriminant analysis (LDA) threshold of > 2.0. Results The LSQ group exhibited significantly higher Shannon alpha diversity than the HSQ group (Tukey’s test, P = 0.048). PCoA combined with PERMANOVA revealed no significant intergroup divergence in overall oral microbial community structure (Bray–Curtis: P = 0.356, R² = 0.0371; unweighted UniFrac: P = 0.414, R² = 0.0353). Six bacterial taxa displayed significantly different relative abundances between groups (all P < 0.05). Actinobaculum timonae and Stomatobaculum longum were enriched in LSQ individuals, whereas Bifidobacterium adolescentis , Bacillaceae , Fusobacterium canifelinum and Haemophilus influenzae were overrepresented in the HSQ group. LEfSe analysis identified 22 discriminatory taxa: LSQ subjects were enriched in Bacteroidota -derived lineages ( Prevotellaceae, Porphyromonadaceae ), while HSQ subjects harbored elevated Deinococcota and Thermus -related taxa. Conclusions Distinct oral microbial taxonomic signatures differentiate adults with good versus poor sleep quality in this Beijing cohort, supporting an intimate link between oral microbiota and sleep status. Longitudinal and interventional trials are required to clarify causal relationships and develop microbiome-targeted strategies for sleep improvement.