Yan Zou,1,2,* Guoli Yan,2,* Minghui Li,2,* Xiaohui Dai,3 Xiaofei Hou,2 Mengmei Wang,2 Ling Sun,2 Huifang Yin,2 Guangming Xu2 

1School of Education, Tianjin University, Tianjin, People’s Republic of China; 2Tianjin Anding Hospital, Mental Health Center of Tianjin Medical University, Tianjin, People’s Republic of China; 3Tianjin Haihe Hospital, Tianjin, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Guangming Xu, Tianjin Anding Hospital, Mental Health Center of Tianjin Medical University, No. 13, Liulin Road, Hexi District, Tianjin, 300222, People’s Republic of China, Tel +86-15122997716, Email xugm@tmu.edu.cn Huifang Yin, Tianjin Anding Hospital, Mental Health Center of Tianjin Medical University, No. 13, Liulin Road, Hexi District, Tianjin, 300222, People’s Republic of China, +86-15922109637, Email yinhf1983@163.com

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.

Keywords: self-harm, chronotype, sleep problems, emotional symptoms, adolescents