Sleep quality and life satisfaction in urban-dwelling solitary Chinese older adults: a study of parallel mediation by depression and cognitive function.

Background: With the rapid aging of the global population, the wellbeing of urban-dwelling older adults living alone is linked to increasing research attention. Methods: Data were derived from the 2017-2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). A sample of 1,261 urban-dwelling older adults living alone was analyzed. Sleep quality, depression, cognitive function, and life satisfaction were assessed. Parallel mediation analysis was conducted using the PROCESS macro (Model 4) with 5,000 bootstrap samples. To validate the robustness of the mediation model, a 5-fold cross-validation procedure was performed, ensuring the stability and association consistency of the indirect effects. Results: Poor sleep quality was significantly associated with higher depression scores and lower cognitive function, both of which were negatively associated with life satisfaction. The mediation analysis revealed that depression and cognitive function independently mediated the relationship between sleep quality and life satisfaction, with depression was associated with a significantly stronger indirect effect (20.22% of total effect) than cognitive function (2.52%). The cross-validated estimates closely matched the full-sample results, confirming model stability. Conclusion: These findings highlight the crucial role of sleep quality in enhancing life satisfaction among urban solitary older adults, primarily in association with the reduction of depressive symptoms. The study highlights the need for community-based interventions integrating sleep hygiene and depression screening, which is particularly relevant to women living alone.