Individual, social, and environmental predictors of insomnia symptom trajectories in a population cohort of Australian adolescents aged 13 to 17 years.

Study Objectives: The aim of this study was to identify heterogeneous insomnia symptom trajectories in a population cohort of adolescents during a developmentally sensitive window (ages 13-17), and to examine the influence of individual, social, and environmental predictors on these different trajectories. Methods: Insomnia symptoms were assessed in a population-based sample of 6377 adolescents via online questionnaires administered annually at school from year 8 (age 13-14) to year 11 (age 16-17). Measures assessing individual, social, and environmental predictors were administered in year 8 only. We used latent class growth analysis to identify insomnia symptom trajectories and multinomial logistic regression to examine individual, social, and environmental predictors associated with each trajectory class. Results: We identified four insomnia symptom trajectories: one "low risk" trajectory (low-stable 55.73%), two "elevated risk" trajectories (increasing 27.49% and high-stable 10.95%), and one "remitting" trajectory (high-decreasing 5.83%). Predictors common to elevated risk trajectories (vs low-stable) were female gender, greater internalizing or externalizing symptoms, and greater negative family interactions. Adolescents with high-stable trajectories were also more likely to be gender diverse or diagnosed with ≥1 disabilities, while adolescents with increasing trajectories were more likely to have ≥1 adverse childhood experiences or lower school connectedness. Male gender was the only predictor significantly associated with a remitting trajectory (vs high-stable). Conclusions: These findings inform future research about the developmental course of insomnia symptoms during adolescence and can guide screening and intervention efforts aimed at improving sleep health for youth at risk of insomnia.