To analyze the impact of nighttime sleep duration on depressive symptoms in the lifestyle habits of elderly people with multiple comorbidities in China.

Using the fifth round of the China Health and Retirement Longitudinal Study project, the depression mood of elderly people with multiple comorbidities was evaluated based on the Center for Disease Control Depression Rating Scale (CSE-D-10). Nighttime sleep was divided into five levels:<6 h, 6 to <7 h, 7 to <8 h, 8 to <9 h, and ≥9 h. Multivariate logistic regression analysis was conducted to investigate the influencing factors of depression in elderly people with multiple comorbidities. Random forest model was used to analyze the importance of nighttime sleep in the risk of depression in elderly people with multiple comorbidities. Restrictive cubic spline curves were used to further explore the dose-response relationship between nighttime sleep duration and the risk of depression.

A total of 1 249 elderly individuals with multiple comorbidities were included, aged (68.51±5.91) years. Multivariate logistic regression analysis showed that the risk of depression in elderly individuals with multiple comorbidities who slept at night for 6 to <7 hours (OR=0.447 (95%CI: 0.309-0.646)), 7 to <8 hours (OR=0.550 (95%CI: 0.351-0.862)), and 8 to <9 hours (OR=0.498 (95%CI: 0.323-0.768)) was relatively lower compared to those who slept for less than 6 hours. Discomfort caused by pain, ADL, life satisfaction, and stroke are the influencing factors for depression in elderly people with multiple comorbidities (P<0.05). The results of the random forest model show that the importance score of nighttime sleep on depression symptoms is relatively high. The results of the restricted cubic spline curve indicate a non-linear relationship between nighttime sleep and the risk of depression symptoms. The risk of depression symptoms decreases with 6-8 hours of nighttime sleep, and increases with less than 6 hours or more than 8 hours of nighttime sleep.

Nighttime sleep has an impact on the occurrence of depression in elderly people with multiple comorbidities. It is recommended that elderly people maintain 6-8 hours of nighttime sleep to effectively reduce the risk of depression and have certain significance for early prevention and control of depression in the elderly population.