Depressive Symptoms, Insomnia-Related Difficulties and Self-Rated Health Among Community-Dwelling Adults Aged 40 Years and Older in Western China: A Cross-Sectional Structural Equation Modelling Study

Background/Objectives: This study examined the associations of depressive symptoms, medical help-seeking attitudes and perceived neighbourhood built environment with self-rated health, including statistical indirect associations through an Insomnia Severity Index (ISI)-derived sleep construct, among community-dwelling adults in western China. Methods: This secondary cross-sectional analysis included 433 adults aged ≥40 years in Gaoping District, Nanchong, China. Self-rated health was assessed using the SF-36 General Health subscale. PHQ-9 and ISI indicators were reverse-coded so that higher values represented lower depressive symptom burden and fewer insomnia-related difficulties, respectively. Structural equation modelling estimated direct and indirect associations, with 5000 bootstrap resamples. Multi-group analysis compared the ISI–self-rated health path between family-functioning groups. Results: Model fit indices were CFI = 0.955, TLI = 0.953 and RMSEA = 0.037. The ISI-derived construct had the largest standardised direct coefficient for self-rated health (β = 0.383, p < 0.001). Reverse-coded PHQ-9 was associated with ISI (β = 0.544, p < 0.001) and self-rated health (β = 0.164, p = 0.009). Medical help-seeking attitudes were directly associated with self-rated health (β = 0.193, p = 0.001). The PHQ-9–ISI–self-rated health indirect estimate was 0.208 (95% CI, 0.134–0.294). Corresponding indirect associations for help-seeking attitudes and neighbourhood environment were not supported. NEWS-A direct paths and the family-functioning group difference were not statistically significant. Conclusions: The findings supported an ISI-related statistical indirect association between depressive symptoms and self-rated health within the specified model. They do not establish causal mediation or intervention effectiveness.