Association between intrinsic capacity, nighttime sleep duration and falls in middle‐aged and older adults: a longitudinal study

Background The association between intrinsic capacity (IC), nighttime sleep duration (NSD), and falls is poorly understood. To that end, the present study aims to explore the association between IC and falls, as well as the mediating role of NSD. Methods Data from four waves of the China Health and Retirement Longitudinal Study (CHARLS) were utilized. The primary measure, IC, was constructed from five dimensions. The relationships between IC, NSD, and falls were assessed using Cox proportional hazards regression models, with a P value of less than 0.05 considered statistically significant. Results This study included 4,789 participants. Over a 7-year period, 1,118 new falls were recorded. In the Cox regression model, higher levels of IC were significantly associated with a reduced risk of falling, both during nighttime sleep and overall. Specifically, for every one-unit increase in IC, the hazard ratio (HR) for falling was 0.863 (95% CI: 0.819,0.909). For every additional hour of nighttime sleep, the HR for falling was 0.936 (95% CI: 0.905,0.967). Mediation analysis revealed that sleep played a mediating role in the association between IC and falling. Conclusions Chinese patients with low IC and a short nighttime sleep duration had a significantly increased risk of falls, highlighting the importance of early assessment and prevention of fall risk.