Co-developmental trajectories of bedtime procrastination and sleep disturbance in adolescents: Predictors and mental health implications.

BACKGROUND: Previous research on bedtime procrastination and sleep disturbance has primarily used variable-centered approaches, leaving their distinct co-developmental patterns during adolescence unclear. This study examined their joint developmental trajectories, psychosocial predictors, and mental health implications. METHODS: A three-wave longitudinal study with approximately six-month intervals was conducted among 1054 Chinese adolescents (mean age = 14.22 years; 58.5% girls). Bedtime procrastination and sleep disturbance were assessed at all waves. Baseline predictors included chronotype, self-control, and intolerance of uncertainty (IU). Generalized anxiety and depression were assessed at baseline and follow-up. Parallel process growth mixture modeling identified joint developmental trajectories, followed by logistic regression analyses examining their predictors and mental health associations. RESULTS: Two co-developmental trajectories emerged: a stable low-risk group (85.1%) with relatively low and stable levels of bedtime procrastination and sleep disturbance, and an escalating-risk group (14.9%) with progressively increasing levels of both over time. Higher IU and evening-type chronotype predicted greater likelihood of escalating-risk membership, whereas higher self-control and morning-type chronotype predicted lower likelihood. Adolescents in the escalating-risk trajectory also showed significantly higher risks and symptom levels of generalized anxiety and depression. CONCLUSIONS: Bedtime procrastination and sleep disturbance follow distinct co-developmental patterns during adolescence. Biological, self-regulatory, and cognitive-affective factors differentiated trajectory membership, and escalating sleep-related maladjustment was associated with poorer mental health outcomes.