Mediating Effects of Sleep Problems and Emotional Symptoms in the Relationship Between Chronotype and Self-Harm Among Adolescents Aged 11-19 Years

Purpose: Self-harm is linked to numerous adverse health and social outcomes, including repetitive self-harm and an increased risk of suicide. This study aims to explore the influence of chronotype on self-harm among adolescents and further investigate the mediating role of sleep problems and emotional symptoms. Participants and Methods: The study was conducted between April and June 2022, involving 13 junior and senior high schools in Tianjin. The participants were asked to complete online questionnaires assessing chronotype, sleep problems, depression, anxiety, and self-harm. The data were analyzed and processed using Spearman correlation and mediation effect analysis. Two mediation pathways were tested: Model 1 with sleep problems and depression as the mediators, and Model 2 with sleep problems and anxiety as the mediators. Results: Participants comprised 13,374 Chinese middle school adolescents (6745 boys) aged 11-19 years. In Model 1, the independent mediation effects of sleep problems and depression were -0.216 (95% CI = [-0.263, -0.172]) and -0.101 (95% CI = [-0.121, -0.083]), accounting for 33.33% and 15.59% of the total effect, respectively. The chain mediation effect was -0.170 (95% CI = [-0.196, -0.146]), accounting for 26.23% of the total effect. In Model 2, the independent mediation effects of sleep problems and anxiety were -0.232 (95% CI = [-0.279, -0.189]) and -0.075 (95% CI = [-0.091, -0.059]), respectively accounting for 35.63% and 11.52% of the total effect. The chain mediation effect was -0.151(95% CI = [-0.176, -0.128]), accounting for 23.20% of the total effect. Conclusion: Chronotype is a significant predictor of self-harm, with a later chronotype associated with a higher risk. Both sleep problems and emotional symptoms independently and serially mediate the relationship between chronotype and self-harm. These findings highlight the complex pathways through which chronotype influences self-harm behavior and suggest potential targets for intervention.