Consequences of Delaying School Start Time on Mental Health Among Adolescents: The START Study

Depression is common among adolescents and can have severe impacts on their well-being. We aimed to determine if delaying high school start times impacts adolescents’ depression risk. Measurement in the START cohort began in Spring 2016 when participants were in 9th grade (baseline, n = 2,134) and all five participating schools started early (7:30 or 7:45 am). Follow-ups 1 and 2 occurred when participants were in 10th and 11th grades by which time two of the schools (“policy-change schools”) had delayed their start times by roughly one hour. Our outcome was the Kandel-Davies depressed mood scale. Difference-in-differences analyses were employed after missing data were multiply imputed with fully conditional specification. Depressed mood scores increased for students in comparison schools relative to policy-change schools at follow-up 1 and at follow-up 2. These differences were primarily driven by the items in the scale related to fatigue. Implementing school schedule policy that is aligned with adolescent circadian biology has the potential to reduce the prevalence of symptoms of depression among cases where fatigue is a primary presenting symptom.