Background: Much attention has been given to the relationship between various training factors and athletic injuries, but no study has examined the impact of sleep deprivation on injury rates in young athletes. Information about sleep practices was gathered as part of a study designed to correlate various training practices with the risk of injury in adolescent athletes. Methods: Informed consent for participation in an online survey of training practices and a review of injury records was obtained from 160 student athletes at a combined middle/high school (grades 7 to 12) and from their parents. Online surveys were completed by 112 adolescent athletes (70% completion rate), including 54 male and 58 female athletes with a mean age of 15 years (SD=1.5; range, 12 to 18 y). The students' responses were then correlated with data obtained from a retrospective review of injury records maintained by the school's athletic department. Results: Multivariate analysis showed that hours of sleep per night and the grade in school were the best independent predictors of injury. Athletes who slept on average= 8 hours. For each additional grade in school, the athletes were 1.4 times more likely to have had an injury (95% confidence interval, 1.2-1.6; P < 0.001). Conclusion: Sleep deprivation and increasing grade in school appear to be associated with injuries in an adolescent athletic population. Encouraging young athletes to get optimal amounts of sleep may help protect them against athletic injuries. Level of Evidence: Level III.