Associations of social jetlag and insomnia symptoms with depressive symptoms among Chinese adolescents: A large population-based study

This study aimed to evaluate the associations of social jetlag and insomnia symptoms with depressive symptoms among adolescents. A total of 37,871 junior high students completed an online survey between May 24th and Jun 5th, 2022. Insomnia symptoms were assessed by three items based on the Diagnostic and Statistical Manual of Mental Disorders criteria. Social jetlag and depressive symptoms were evaluated by the Munich Chronotype Questionnaire and the Patient Health Questionnaire, respectively. Restricted cubic splines were used to explore the relationship between social jetlag and depressive symptoms. Joint effects of social jetlag and insomnia symptoms on depressive symptoms were estimated using additive interaction models. The prevalence of depressive symptoms was 13.1%. Depressive symptoms were more common in adolescents with social jetlag ≥2 h (OR: 1.51, 95% CI: 1.39–1.65) and insomnia symptoms (OR: 6.91, 95% CI: 6.41–7.44). There was a J-shaped relationship between social jetlag and depressive symptoms when we took social jetlag as a continuous variable. Moreover, a positive additive interaction of social jetlag ≥2 h and insomnia symptoms on depressive symptoms was found in female adolescents (RERI: 2.30, 95% CI: 0.11–4.49). Our findings suggested that social jetlag ≥2 h and insomnia are related to the occurrence of depressive symptoms in adolescents. Their coexistence additively enhances the strength of the association with depressive symptoms. Early screening and intervention for insomnia, as well as methods to reduce social jetlag, should be comprised as part of preventive strategies for depression in adolescents.