Relationships between school start time, sleep duration, and adolescent behaviors.

Objectives: The objectives were 2-fold: (1) to examine how high school start times relate to adolescent sleep duration, and (2) to test associations between sleep duration and mental health- and substance use-related issues and behaviors in teens.

Design: This study examines selected questions from survey data collected between 2010 and 2013 high school students.

Setting: Respondents included more than 9000 students in grades 9 to 12 in 8 high schools in 5 school districts across the United States.

Measurements: The survey instrument is the 97-item Teen Sleep Habits Survey. Logistic regression models were used to calculate adjusted odds ratios and 95% confidence intervals. Because of clustering within schools and the use of repeated measures, generalized estimating equations were used to account for variance inflation.

Results: Greater sleep duration was associated with fewer reports of various mental health- and substance use-related issues and behaviors (all P values <.01). For instance, for each additional hour of sleep reported, there was a 28% reduction in the adjusted odds of a participant reporting that he or she felt "unhappy, sad, or depressed." Later wake-up times were associated with a reduction in risk for some, but not all factors. Later start times were significantly associated with greater sleep duration.

Conclusions: 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.