IMPORTANCESleep is a resource that has been associated with health and well-being; however, sleep insufficiency is common among adolescents. OBJECTIVE To examine how delaying school start time is associated with objectively assessed sleep duration, timing, and quality in a cohort of adolescents. DESIGN, SETTING, AND PARTICIPANTSThis observational cohort study took advantage of district-initiated modifications in the starting times of 5 public high schools in the metropolitan area of Minneapolis and St Paul, Minnesota. A total of 455 students were followed up from grade 9 (

Given that later start times allow for greater sleep duration and that adequate sleep duration is associated with more favorable mental health- and substance use-related issues and behaviors, it is important that school districts prioritize exploring and implementing policies, such as delayed start times, that may increase the amount of sleep of adolescent students, which is needed for their optimal development.

Introduction: Short sleep duration is exceedingly common among adolescents and has implications for healthy youth development. We sought to document associations between adolescents' sleep duration and characteristics of their schedules, behaviors, and wellbeing. Methods: We used data from the baseline wave (9th grade year) of the START study, a cohort of 2134 students in ive Minnesota high schools to assess how self-reported sleep duration was associated with the prevalence of time-use characteristics (i.e. activity schedules, screen use), sleep-wake problems (i.e. trouble waking in the morning, falling asleep in class, etc.), and risk of depression.Results: Shorter sleep duration was associated with various behaviors including greater computer/screen time and screen use after bed, a lower probability of doing homework, participation in sports doing chores on school nights, and reporting that it takes at least 20 min to fall asleep on school days (p < 0.05). Suboptimal sleep duration was also associated with a higher probability of all reported sleep-wake problems as well as higher risk of depressive symptoms (p < 0.05). Conclusions: Given that getting an optimal amount of sleep can protect youth from risk and promote healthy youth development, it is critical that we gain a greater understanding of correlates and consequences of short sleep duration in order to develop a sleep-friendly culture for youth.