The Effect of Night Shift Work on the Gut Microbiome Diversity: The EXPONIT Study

Night shift work may alter the gut microbiome through mechanisms involving circadian misalignment, sleep disturbance, and changes in dietary behavior. However, existing studies on this topic have been limited in sample size and scope. We analyzed stool samples from 240 participants (mean age 42 years, 80% women), of whom 53% were night shift workers. Gut microbiota composition was assessed using 16S rRNA gene sequencing to derive measures of relative abundance, alpha diversity, and beta diversity. Associations between night shift work and microbial composition and alpha diversity were examined using generalized linear models with a Gamma distribution and log link for alpha diversity and Aitchison distance for beta diversity. The effect of night shift work on microbiome genera abundance was evaluated using MaAsLin2 analysis. Models were adjusted for age, sex, and educational level. We also explored potential interactions by sleep quality, diet, and chronotype. There were no overall significant differences in alpha or beta diversity between day and night shift workers, but participants with less than 15 years of night work showed slightly higher Abundance-based Coverage Estimator than non-night workers. Interaction with sleep quality was observed ( p -value: 0.01). Among participants with poor sleep quality, night shift work was significantly associated with lower alpha diversity (exp(β): 0.93, 95% CI: 0.87-0.99, p -value: 0.02). Day shift workers showed high relative abundance of Ruminococcus , while night shift workers had increased Escherichia-Shigella at descriptive level, none of which remain statistically significant after false discovery rate. Our findings indicate that night shift work may influence gut microbiome diversity, especially in individuals with poor sleep quality. Future research should explore the long-term health consequences of these microbial changes.