Association of disrupted circadian rhythms with self‐reported periodontal diseases: Insights from 94,305 UK Biobank participants

BACKGROUND: This study investigates the association of circadian rhythmicity, physical activity, and chronotype with periodontal diseases, focusing on both the independent and combined effects. METHODS: A cross-sectional study was conducted among 94,305 participants from the UK Biobank. Circadian rhythmicity, measured by relative amplitude from the accelerometer, was the primary exposure, with physical activity and chronotype (morning/evening preference) as secondary exposures. Self-reported periodontal diseases were the outcome of interest. Multivariable logistic regression and restricted cubic splines were used to evaluate linear and nonlinear associations, including interactions between exposures. RESULTS: Each standard deviation increase in relative amplitude was associated with a 3% lower risk of periodontal diseases (odds ratio, OR: 0.97, 95% confidence interval, CI: 0.95-0.99). A 10 milligravity increase in physical activity was associated with a 10% reduction in risk (OR: 0.90, 95% CI: 0.87-0.92). An evening chronotype increased the risk by 23% (OR: 1.23, 95% CI: 1.15-1.32). Both additive and multiplicative interactions were observed between physical activity and chronotype, as evidenced by the relative excess risk due to interaction (RERI) and attributable proportion (AP), with confidence intervals excluded the null, and a synergistic effect on the multiplicative scale (OR: 1.13, 95% CI: 1.03-1.24). A nonlinear association between physical activity and periodontal diseases was observed. CONCLUSIONS: Disrupted circadian rhythms, lower physical activity, and an evening chronotype are independently and interactively associated with an elevated risk of periodontal disease. Interventions promoting circadian alignment and increasing physical activity may represent promising strategies to explore in future studies aiming to reduce periodontal risk. PLAIN LANGUAGE SUMMARY: Modern life, with long hours and shift work, can disrupt our natural daily body clocks. This study looked at whether these disrupted rhythms, along with how much we move and whether we are "morning people" or "night owls", affect oral health. Using wearable devices worn by over 94,000 UK adults, researchers found that people with smaller differences in activity between their most active and least active times of day had a higher risk of periodontal disease. Being more physically active was strongly associated with a lower risk, while people who naturally preferred being active later in the day ("night owls") had a higher risk. Importantly, the combination of being a "night owl" and having low physical activity posed the greatest risk, higher than just adding the two risks together. This suggests that keeping a regular daily activity pattern (being more active during the day and less at night), getting enough exercise, and perhaps trying to lean towards a morning routine could all be important ways to maintain oral health. While more research is needed, especially to see if changing these habits actually prevents periodontal disease, these findings point to promising new approaches for maintaining oral health.