Sleep duration trajectory during the transition to adolescence and subsequent risk of non-suicidal self-harm

Non-suicidal self-harm (NSSH) and chronic insufficient sleep are both major health problems during the transition from childhood to adolescence. We examined to identify sleep duration trajectories from childhood to adolescence and their associations with subsequent risk of NSSH. A cohort of children around the period of pubertal onset (7-9 years old) were followed from 2013 over 6 years. Group-based trajectory modeling was recruited to identify sleep duration trajectories derived from 5 repeated measures. Association between sleep duration trajectories with the risk of NSSH was examined using multivariate logistic regression model. Nonlinear dose-response associations between sleep duration and NSSH risk were also assessed using restricted cubic spline models. Of the 1973 participants included in the study (mean ± SD, 8.1 ± 0.9 years age at baseline, 41.1% female). Three sleep duration trajectories were identified: persistent sleeping ≥ 8 h/day (27.7%), moderately decreasing (60.8%) and rapidly decreasing (11.5%) sleep duration groups. After multivariable adjustment for covariates, compared with the persistent sleeping ≥ 8 h/day group, the odds ratio of NSSH was 2.58 (95% CI 1.92, 3.45) for the moderately decreasing group, and 4.16 (2.86, 6.04) for rapidly decreasing group. In dose-response analysis, sleep duration was associated with NSSH risk in a non-linear fashion (χ² = 25.16, P_nonlinearity < 0.001). When compared with the reference (sleep duration = 8 h), the ORs (95% CI) for NSSH risks were 3.20 (1.93, 5.29), 2.37 (1.64, 3.41), 1.75 (1.39, 2.20) and 1.30 (1.18, 1.44) for sleep duration at 4 to 7 h, respectively. Also, we found sleep duration at 9 h [0.82 (0.75, 0.89)] and at 10 h [0.72 (0.57, 0.91)] significantly associated with decreased risk of NSSH. Longitudinal sleep duration patterns may assist in identification of adolescents at greatest risk of NSSH in the future, which could lead to improved targeting of prevention and intervention strategies. The findings also highlight a non-linear relationship between sleep duration and NSSH during the transition to adolescence.