Abstract
<title>Abstract</title> <p>Background Chronic pain and depression frequently coexist and impose a substantial health burden among middle-aged and older adults. This study examined the associations of pain location and pain burden with depressive symptoms and the mediating role of sleep duration. Methods Data were obtained from the 2020 China Health and Retirement Longitudinal Study (CHARLS). After excluding participants with missing data, 15,317 adults aged ≥ 45 years were included. Depressive symptoms were assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10). Pain was assessed across 15 anatomical sites. Multivariable logistic regression, restricted cubic spline, mediation, and interaction analyses were performed. Results A total of 5,790 participants (37.8%) had depressive symptoms. Pain at all anatomical sites was significantly associated with depressive symptoms. Chest pain showed the strongest association (OR = 3.04, 95% CI: 2.69–3.43). Compared with participants reporting no pain, those with ≥ 5 painful sites had more than fourfold higher odds of depressive symptoms (OR = 4.25, 95% CI: 3.86–4.68). Each additional painful site increased the odds of depressive symptoms by 17.7% (OR = 1.177, 95% CI: 1.164–1.191). A significant nonlinear dose–response relationship was identified (P < 0.001). Sleep duration partially mediated the association, accounting for 12.1% of the total effect, whereas no significant interaction was observed. Conclusions Pain location and pain burden were independently associated with depressive symptoms. Depression risk increased nonlinearly with increasing pain burden, and sleep duration partially mediated this association, supporting integrated pain and psychological management in middle-aged and older adults.</p>