Impact of Sleep Quality on Depressive Symptoms in Adolescents: The Mediating Role of Coping Strategies and Limited Moderating Effect of Self-Efficacy

Background Adolescence is a critical developmental stage characterized by emotional challenges and an increased vulnerability to depressive symptoms (DS). While poor sleep quality (PSQ) is known to correlate with DS, the roles of coping strategies (CS) and self-efficacy (SE) in this relationship remain underexplored.This study investigates the relationships between sleep quality (SQ), CS, SE and DS among adolescents, emphasizing the mediating role of CS and the moderating role of SE in the SQ-DS relationship. Methods Utilizing a cross-sectional design, data were collected from 1,132 junior high school students in China between January and June 2023.Participants completed self-report questionnaires assessing the Self-Rating Depression Scale (SDS), the Pittsburgh Sleep Quality Index (PSQI), the Simplified Coping Style Questionnaire (SCSQ), and the General Self-Efficacy Scale (GSES). Descriptive statistics, correlation analysis, regression analysis, and mediation-moderation analysis using PROCESS were conducted to examine variable relationships. Results The findings revealed a significant positive relationship between PSQI and SDS (Beta = 0.350, p < 0.001), indicating that PSQ is associated with higher levels of DS. CS acted as a mediator; specifically, positive coping (SCSQ.AR) negatively predicted SDS (Beta = -0.432, p < 0.001), whereas negative coping (SCSQ.NC) positively predicted SDS (Beta = 0.270, p < 0.001). GSES did not significantly moderate the direct relationship between PSQI and SDS (B = -0.0076, p = 0.5437), but it partially moderated the indirect effects through negative coping. Adolescents with lower SE were more prone to adopt negative coping strategies (NCS), which in turn exacerbated their DS. Conclusion PSQ is significantly associated with increased DS in adolescents, with NCS intensifying this relationship, especially among those with lower SE. Although enhancing SE alone may not significantly influence the direct impact of PSQ on DS, interventions that promote positive coping strategies (PCS) and reduce NCS, combined with efforts to enhance SE, could effectively alleviate DS. Future research should adopt a longitudinal approach to further elucidate these relationships and inform targeted mental health interventions for adolescents.