Association between nap time, nighttime sleep, and mild cognitive impairment in Chinese older adults: a cross-sectional study

Abstract Objective This study aims to investigate the relationship between midday nap time, nighttime sleep duration, and mild cognitive impairment (MCI) in Chinese older adults and determine the recommended sleep duration to provide a scientific basis for preventing and managing MCI in this population. Methods Utilizing the 2020 China Health and Elderly Care Longitudinal Survey database, the demographic data, health status, and lifestyle information of the study participants were collected. A total of 5,314 valid samples were included in the analysis. Logistic regression and restricted cubic spline plots were employed to explore the relationship between sleep patterns and MCI. Results In the cross-sectional analysis, a linear relationship was observed between midday nap duration and MCI among Chinese elderly. The probability of MCI was lowest among those who napped for less than 30 minutes at noon. Compared with individuals who napped for less than 30 minutes, those who did not nap were more likely to have MCI (OR = 1.39, 95% CI: 1.08–1.81). Nighttime sleep duration exhibited a U-shaped relationship with MCI. Individuals with less than approximately 6.5 hours of nighttime sleep showed a gradual decrease in the probability of MCI with increasing sleep duration, whereas those with more than 6.5 hours demonstrated an increase in the probability of MCI with longer sleep duration. Older adults who slept less than 6 hours at night (OR = 1.24, 95% CI: 1.05–1.48) or more than 8 hours (OR = 1.79, 95% CI: 1.37–2.34) were at a higher risk of developing MCI compared with those who slept 6 to 8 hours. Conclusion After controlling for potential confounders, midday napping is beneficial in preventing MCI among older adults. Nighttime sleep duration exhibited a U-shaped relationship with MCI risk, with the optimal range for health benefits observed between 6 and 8 hours of sleep duration, approximately 6.5 hours.