Association of Long Sleep and Physical Inactivity with Incident Disability in Community-Dwelling Older Adults: A 5-Year Longitudinal Study

Background: Good sleep durations and physical activity are essential factor for maintaining good health. This study examined whether sleep duration and physical inactivity were associated with incident disability among community-dwelling older adults. Methods A total of 4,372 adults aged ≥ 70 years participated in a baseline assessment. We also assessed self-reported sleep duration and physical activity using the International Physical Activity Questionnaire – Short Form at baseline assessment. We measured monthly incident disability, defined as the onset of being certified for personal support or care as required by Japanese public long-term care insurance over 5 years. The Cox proportional hazard regression analysis estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for incident disability according to long sleep duration (≥ 9 h) and physical inactivity. Results Long sleep duration (HR 1.32, CI 95% 1.05–1.67) and physical inactivity (HR 1.33, CI 95% 1.13–1.57) were associated with incident disability in multivariate analyses. These results were also sustained in the model where both long sleep duration and physical inactivity were simultaneously submitted as independent variables. Furthermore, coexistence of long sleep duration and physical inactivity had higher risk of incident disability than each factor individually (HR 1.69, CI 95% 1.11–2.58), even though the synergistic interaction was mildly effective. Conclusions This study revealed that long sleep duration and physical inactivity were independently associated with the risk of incident disability among older adults. More attention should be paid to both sleep duration and physical activity in order to prevent incident disability.