Associations of self-reported and actigraphic sleep with gut microbiome composition and diversity among older adults

Study Objectives Poor sleep is linked to adverse health outcomes. Animal studies suggest the gut microbiome may influence sleep, but human findings remain inconsistent. We examined associations of self-reported insomnia symptoms, daytime sleepiness, and actigraphy-measured sleep with gut microbiome diversity and composition in older adults. Methods We studied 869 Baltimore Longitudinal Study of Aging participants with self-reported sleep and shotgun metagenomic sequencing; 332 also had actigraphy. We tested associations of sleep with alpha diversity, beta diversity, and species composition using regression, PERMANOVA, and ANCOM-BC2, adjusting for age, sex, BMI, physical activity, education, and depressive symptoms. Results Participants had mean age 70.7 years; 54.8% were female and 66.9% White. Trouble falling asleep ≥5 times/week was associated with higher Shannon diversity (β=0.41 SD; 95% CI: 0.09, 0.73) and Pielou’s evenness, but not richness metrics. No actigraphy-measured sleep variables were associated with alpha or beta diversity. Beta diversity analyses suggested excessive sleepiness (1-2 o 3-4 times/week) was associated with different microbial composition, though variance explained was small. In species-level analyses, frequent insomnia symptoms or excessive sleepiness were associated with depleted or undetected Eubacterium sp. CAG:251. In exploratory actigraphy models, each doubling of sleep efficiency was associated with higher Eubacterium sp. CAG:251 prevalence (PR=2.15; 95% CI: 1.47, 3.14), while each 30-minute increase in wake after sleep onset was associated with lower prevalence (PR=0.49; 95% CI: 0.29, 0.81). Conclusions Global diversity findings were limited and inconsistent, whereas subjective and objective sleep disturbances converged on Eubacterium sp. CAG:251. Findings are exploratory and require longitudinal replication.