Drowsy driving and teen motor vehicle crashes: Impact of changing school start times

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.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).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.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.