Abstract: This paper aims to discuss the mediating effect of activity of daily living (ADL) and life satisfaction between sleep duration and depression in the elderly, and to reveal the pathways through which sleep affects depression. Based on data from the 2020 China Health and Retirement Longitudinal Study (CHARLS), a total of 8 323 individuals aged 60 years and above were included. The Katz Scale, the Life Satisfaction Questionnaire, and the Chinese version of the CES-D10 Scale were used to assess ADL, life satisfaction, and depression, respectively. The bootstrap method was employed to test the chain mediating effect. The results showed that sleep duration was negatively correlated with depression (c = -0.111, P < 0.001). ADL and life satisfaction played a chain mediating role between sleep duration and depression, with an indirect effect of -0.002 4 (95% CI: -0.003 4, -0.001 5), indicating that sleep duration indirectly affected depression in the elderly by affecting ADL and life satisfaction. Therefore, it is recommended to popularize scientific sleep knowledge through community health education to guide the elderly towards healthy sleep; to strengthen ADL rehabilitation training and assistive device guidance to delay functional decline; to organize diverse social and cultural activities to enhance life satisfaction among the elderly; to provide timely psychological support such as cognitive behavioral therapy to individuals at risk of emotional problems, thereby blocking the pathway to depression; and to systematically build a support network integrating community-based medical services and social support, forming a complementary mental health protection system for the elderly.