Associations between perceived stress, sleep quality, and suicidal ideation among Chinese graduating-grade secondary school students: a multi-method study of the moderating role of physical exercise.

Objective: This study aimed to investigate the associations among perceived stress, sleep quality, physical exercise, and suicidal ideation among Chinese graduating-grade secondary school students. Specifically, this study examined whether sleep quality mediated the association between perceived stress and suicidal ideation and whether physical exercise moderated these relationships. In addition, machine-learning prediction models and network analysis were applied to identify important predictors and interconnected symptoms associated with suicidal ideation. Methods: A cross-sectional survey was conducted among ninth- and twelfth-grade students from 13 secondary schools in Yunnan Province, China. A total of 4,372 valid questionnaires were collected. Participants completed measures of perceived stress, sleep quality, suicidal ideation, and physical exercise. Mediation and moderated mediation analyses were conducted using PROCESS models after adjusting for demographic covariates. Furthermore, ridge regression and gradient boosting tree models were used to predict suicidal ideation, with Shapley additive explanations (SHAP) applied to evaluate predictor contributions. Network analysis was conducted to explore central and bridge nodes among study variables. Results: Perceived stress was positively associated with suicidal ideation, and sleep quality partially mediated this association. Physical exercise significantly moderated the direct association between perceived stress and suicidal ideation as well as the association between sleep quality problems and suicidal ideation. Specifically, higher levels of physical exercise weakened the positive relationships between perceived stress, sleep problems, and suicidal ideation. Machine-learning analyses showed that sleep quality problems, perceived stress, physical exercise, and their interaction terms contributed substantially to the prediction of suicidal ideation, with both models achieving an R Conclusion: Among Chinese graduating-grade secondary school students, perceived stress, poor sleep quality, and suicidal ideation were closely interconnected, whereas physical exercise appeared to attenuate these risk associations. Integrating stress management, sleep improvement strategies, and regular physical exercise into school-based mental health programs may provide potential approaches for suicide risk prevention among adolescents.