Longitudinal relationships across sleep, physical activity, and mental wellbeing in early-to-mid-adolescence: A developmental cascades investigation

Purpose: Sleep (SL), physical activity (PA), and wellbeing (WB) are three factors linked to positive development in adolescence. Despite theoretical support and some empirical evidence of developmental associations between these factors, few studies have rigorously investigated reciprocal associations over time separating between-person and within-person effects, and none have investigated all three in concert. Thus, it remains unclear how the interplay between sleep, physical activity and wellbeing unfolds across time within individuals. This study examines this question in the crucial early-to-mid-adolescence developmental transition. Method: Separating within- and between-person effects, a random-intercept cross-lagged panel model will be fitted to a dataset of N= [to be completed in Stage 2 submission] adolescents (age 12/13 at first timepoint) from Greater Manchester, England, using a three-by-three design (three annual timepoints: T1, T2, T3; three variables: SL, PA, WB). Results: [to be completed in Stage 2 submission]. Conclusion: [to be completed in Stage 2 submission].