Investigating the Longitudinal Bi-Directional Relationship between Restrictive-Type Disordered Eating and Sleep in UK Adolescents within the Millennium Cohort Study

Objective: This study aimed to investigate the longitudinal bi-directional relationship between restrictive-type disordered eating behaviours and self-reported sleep characteristics within a sample of UK adolescents from the Millennium Cohort Study (MCS). Method: Using a Structural Equation Modelling approach, the present study investigated the prospective associations between individual sleep behaviours (e.g., sleep timing, sleep onset latency, social jetlag) at age 14 and restrictive-type disordered eating at age 17. Moreover, the association between restrictive-type disordered eating (age 14) and self-reported sleep quality (age 17) was tested. A mediation analysis was conducted to explore the role of depressive symptoms in these relationships. In total, N=6,041 young people provided self-report data at both timepoints (sweep 6 & 7) and a subsample of N=2,164 additionally provided diary data on their sleep behaviours over two separate 24h periods. Results: Sleep indicators at age 14 did not significantly predict changes in disordered eating across time. However, engagement in restrictive-type disordered eating behaviours at age 14 significantly predicted poorer self-perceived sleep quality three years later (β=.06, SE=.01, p<.01). Depressive symptoms fully mediated this relationship (indirect effect: β=.05, SE=.04, p<.001).Discussion: The present study provides evidence for a prospective positive association between restrictive-type disordered eating and subsequent poorer sleep quality in a large, general population sample. Findings of the mediation analysis suggest mood as an important target for tertiary prevention when addressing disordered eating behaviours in adolescents.