Nonlinear Associations Between Sleep Duration and Dementia: Evidence from the CHARLS and Mendelian Randomization Analysis.
TL;DR
Optimizing sleep duration and managing insomnia may help reduce dementia risk in Chinese middle-aged and older adults.
Abstract
Dementia poses a substantial global health burden, necessitating public health focus on modifiable risk factors. While sleep duration has been linked to dementia risk, studies specifically addressing middle-aged and older Chinese adults remain limited. Using cross-sectional (n=12,187) and longitudinal (n=9,030, 4-year follow-up) data from CHARLS, along with two-sample Mendelian randomization (MR), we examined associations between sleep duration and dementia, and causality between insomnia and dementia. We observed the strongest dementia risk among individuals reporting extreme sleep durations (<5h or >10h), both cross-sectional (OR=2.99, 95% CI: 2.47-3.62, P<0.001) and longitudinally (HR=1.55, 95% CI: 1.25-1.91, P<0.001). Restricted cubic spline analyses demonstrated a significant U-shaped dose-response association (P for nonlinearity <0.001). MR findings provided suggestive evidence for a potential causal effect of insomnia on dementia risk (OR=1.06, 95% CI: 1.01-1.13, P=0.029). Sensitivity analyses confirmed robustness. Optimizing sleep duration and managing insomnia may help reduce dementia risk in Chinese middle-aged and older adults.