Sleep duration and cognitive function among rural older adults in China: a population- based study

Abstract

Background The appropriate sleep duration is essential for maintaining normal cognitive function, but evidence is scarce in rural elderly population. This study investigates the associations between self-reported sleep duration and cognitive function among older adults in rural China. Methods This population-based cross-sectional study used data from the Confucius Hometown Aging Project in Shandong, China. Data on demographics, lifestyles, and chronic health conditions were collected through interviews, clinical examinations, and laboratory tests. Sleep duration was classified into four groups (≤ 5, 6, 7, and ≥ 8 h/day). The Mini-Mental State Examination (MMSE) was used to assess the global and domain-specific cognitive function. Linear and logistic regression were performed to determine the associations between sleep duration and cognitive function. Results There was a U-shaped relationship between sleep duration and cognitive impairment. Compared with 6 hours’ sleep per day, sleeping ≤ 5 hours and ≥ 8 hours per day was associated with cognitive impairment, with odds ratio (95% confident interval) being 1.66 (1.02, 2.70) and 1.77 (1.07, 2.92) respectively. Compared with those sleep 6 hours per day, those sleep 5 hours per day or less had lower score of attention and calculation (β = -0.21, 95% confidence interval= -0.38, -0.05), those sleep 8 hours or more had lower score of orientation, attention and calculation, delayed recall, and linguistic competence (β range from − 0.08 to -0.22). Conclusions There is a U-shape relationship between sleep duration and cognitive impairment in rural Chinese older adults.