Background <p>Sleep disturbances represent a prevalent health concern among the elderly population, exhibiting significant correlations with chronic diseases and substantially diminishing quality of life. Chronic conditions may indirectly impact sleep quality through somatic pain and depressive symptoms; however, this chain mediation mechanism remains inadequately supported by empirical research. This study aims to investigate the relationship between chronic diseases and sleep disturbances in the elderly population, while examining the chain mediation effects of somatic pain and depressive symptoms between these variables.</p> Design <p>This study was a cross-sectional study that used a structural equation model to test the chain mediating effect.</p> Methods <p>Data from 7,631 elderly people aged 60 and above in the 2018 China Health and Retirement Longitudinal Study (CHARLS) were utilized. Statistical analysis was conducted using SPSS 26.0 and the PROCESS macro program. The number of chronic diseases was the independent variable, sleep duration was the dependent variable, and somatic pain and depressive symptoms were the mediating variables for the chain mediating effect test.</p> Results <p>The number of chronic diseases in the elderly was negatively correlated with sleep duration (<i>β</i> = -0.36, <i>P</i> &lt; 0.001). Somatic pain and depressive symptoms played a significant chain mediating role between chronic diseases and sleep, accounting for 25.53% of the total effect.</p> Conclusions <p>The more chronic diseases the elderly have, the shorter their sleep duration at night. Somatic pain and depressive symptoms play a chain mediating role in the process by which chronic diseases affect sleep, suggesting that medical staff should pay attention to pain management and mental health intervention for elderly patients with chronic diseases to improve their sleep quality.</p>