RESUMO
INTRODUCTION: Motor vehicle crashes (MVC) are the second leading cause of death for adolescents in the United States, with drowsy driving a major contributing factor. Early school start times have been identified as a significant factor that reduces adolescent sleep duration, which in turn contributes to drowsy driving and MVC. This paper examined the longitudinal impact of delaying secondary school start times on self-reported student drowsy driving and teen MVC. METHODS: Secondary school students (10th and 11th grade, 51.7% female, 67.8% White) in the United States completed annual surveys 1 year before and 2 years after implementation of later school start times (70-min delay, n range 1642-2452 per year), reporting frequency of drowsy driving (less than once/week vs. at least once/week). Teen (16-18 years) MVC data from the Colorado Department of Transportation for the 2 years before and 2 years after later start time implementation were compared for Arapahoe County (where start times changed) and neighboring Adams County and Douglas County (where start times did not change). RESULTS: With later start times, there was a significant drop in the percent of students who reported frequent drowsy driving (pre-change: 32.6%, post-change: 21.9%, follow-up: 22.8%). Weekday teen MVC rates went down in Arapahoe County (p = .04) during the school year, while no change or increases in MVC rates were seen in neighboring counties. CONCLUSIONS: Healthy school start times are important for adolescent health and safety, with study findings highlighting the downstream effects of increased sleep duration following a 70-min delay in secondary school start times on adolescent drowsy driving and teen MVC rates.