Depressive symptoms are associated with short and long sleep duration: A longitudinal study of Chinese adolescents

•Sleep loss and irregular sleep patterns in adolescents are a major public health concern.•Both short and long sleep duration on weekdays and weekends are related to depressive symptoms.•Weekday-weekend sleep imbalance is related to depressive symptoms. Sleep loss and irregular sleep patterns in adolescents are major public health concerns in the modern society. This study aimed to explore the associations between short and long sleep duration and depressive symptoms among Chinese adolescents. A total of 7311 adolescents who participated in the baseline survey and were followed up 1 year or 2 years later were included in the analyses. Participants completed a self-administered questionnaire at baseline and follow-up surveys. The Center for Epidemiologic Studies Depression (CES-D) scale was used to assess depressive symptoms. Generalized estimating equation (GEE) and restrictive cubic spline models were used to estimate the association between sleep duration and depressive symptoms. After adjusting for adolescent and family covariates, sleep duration =9 h on weekdays and sleep duration =12 h on weekends were significantly associated with depressive symptoms compared with sleep 8 h. Weekend-weekday sleep difference >=3 h or 1 h on weekdays than weekends) was also associated with depressive symptoms. There were U-shaped relationships between sleep duration on weekdays, weekends, or weekday-weekend sleep difference and depressive symptoms. Sleep duration and depression were measured by self-report. Our findings highlight the risk of short and long sleep duration, and weekday-weekend sleep imbalance for depression in adolescents.