In this issue of JAMA Pediatrics, Martiniuk et al1 prospectively followed up a large cohort of 19 327 Australian new drivers aged 17 through 24 years. Drivers were asked to describe their hours of sleep overall, as well as their typical hours of sleep on weekends. Participants were also asked about other important injury risk factors including alcohol and drug use. These survey data were linked prospectively to licensing data and police-reported crashes over the following 2 years. Crash risk was adjusted for a number of important confounders: time in the study, prior crashes, age group, sex, average weekly driving hours, remoteness of residence, drinking behavior (Alcohol Use Disorders Identification Test score), risky driving behaviors, self-harm, drug use, sensation seeking, and psychological distress.