Young Drivers and the Risk for Drowsy Driving

In this issueofJAMAPediatrics,Martiniuketal1prospectivelyfollowed up a large cohort of 19 327 Australian new drivers aged 17 through24years.Driverswere asked todescribe their hours of sleepoverall, aswell as their typical hours of sleeponweekends.Participantswerealsoaskedaboutother important injury risk factors including alcohol anddruguse. These surveydata were linkedprospectively to licensingdataandpolice-reported crashes over the following 2 years. Crash riskwas adjusted for a number of important confounders: time in the study, prior crashes, agegroup, sex, averageweeklydrivinghours, remoteness of residence, drinking behavior (Alcohol Use Disorders Identification Test score), risky driving behaviors, self-harm, drug use, sensation seeking, and psychological distress. They found that those who said they slept fewer than 6 hours each night were at increased risk for crash compared with those who reported getting more than 6 hours of sleep (relative risk, 1.21; 95% CI, 1.04-1.41). Crashes for individuals with less sleep per night (on average and on weekends) were significantly more likely to occur in the evening hours between 8 PM and 6 AM (relative risk, 1.86; 95% CI, 1.11-3.13). Individuals who slept 6 or fewer hours each night were also more risky on nearly every measure studied: they had more prior crashes, drove more each week, and had higher reported alcohol and drug use. The authors do not describe police-reported risk factors identified at the crash, such as suspected alcohol use or contributing factors, which might have provided evidence of associated risks in this cohort. Themagnitude of the increased crash risk (1.21) was comparatively lowrelativetootherriskfactorssuchasreportedcrash risk fromalcohol (estimatedcrash relative riskof 27.4 foryoung drivers 17-20yearsofagewithbloodalcohol level>.08,andrelative risk of 4.62 for young drivers 21-24 years of age).2 However, this riskwasbasedonaveragereportedsleepandmayhave beenmuch higher for individual trips for a drowsy individual. Martiniuk et al1 found that the youngest drivers reported slightly higher average hours of sleep than the older groups in their study, which may have been owing to pressures from work. However, nearly 10% of 17-year-old participants and 17% of 20to 24-year-old subjects reported getting fewer than 6 hours of sleep per night. From the public health perspective, one important question is to examine what potentially modifiable factors may reduce crash risk from drowsy driving. Sleep habits have changed substantially over time,3 and young people experience significant health consequences and reduction in driving performance with sleep deprivation.4-6 The growth in late-night media and technology use may be further jeopardizing healthy sleep for young people.7 Parents can play a role in setting guidelines for healthy sleep, late-night screen time, and driving restrictions. Nighttime driving restrictions for novice young drivers are a standard part of the graduated driving laws. The increased nighttime crash rates described in this study provide further support for the potential benefit of nighttime driving restrictions. Other measures that make it easier to identify novice drivers, such as license-plate decals, hold promise for improving compliance with and enforcement of graduated driving laws and reducing crash risk.8 Young drivers sleeping few hours a night were also more likely to have other high-risk behaviors. They were more likely to drink regularly and use other drugs, and they scored higher on measures of risk taking and sensation seeking. In the study by Martiniuk et al, drivers reporting less sleep were more likely to have crashed in the past. The impact of other crash risk factors, such as alcohol, confers greater risk for young people than for older, more experienced drivers.2 Younger people, who have not fully integrated their driving skills, are particularly vulnerable to behaviors that impair response times and driving performance. Interventions that have been effective for reducing impaired driving remain important tools for reducing the burden of road traffic injury for all ages. Driving remains one of the riskiest activities that young people undertake.9 Seeking interventions that address these risks is a critical public health challenge.10 The longitudinal study by Martiniuk and colleagues provides impetus for seeking public health approaches to reducing drowsy driving, improving enforcement of nighttime driving restrictions for novice drivers, and further exploring the cluster of high-risk driving behaviors among young drivers.