Study objectives: Extended duration (≥24 hours) work shifts (EDWSs) are associated with increased risk of motor vehicle crashes, and awareness of any impairment has important implications on legal accountability for any adverse driving outcome. The extent to which adverse driving events were preceded by predrive self-reported sleepiness was evaluated in medical residents after an EDWS.
Methods: Sixteen resident physicians (10 females; 29.2 ± 2.0 years) working EDWS were monitored when driving on their commute to and from the hospital (438 drives). Sleep and work hours were obtained from daily logs, and adverse driving outcomes were captured from a driving log completed at the end of each drive. Self-reported sleepiness (Karolinska Sleepiness Scale; KSS) and objective drowsiness were captured using a time-stamped, hand-held device and infra-red reflectance oculography.
Results: Self-reported sleepiness and objective indices of drowsiness were positively correlated, and both were elevated following EDWSs. Compared with the commute to work, EDWSs were associated with more than double the self-reported adverse outcomes when driving home, significantly higher than drives to or from the day shift at comparable times of day. EDWSs more than tripled the odds of reporting sleep-related, inattentive, hazardous, or violation-driving events. The number and type of adverse event was predicted by the predrive KSS level and in a dose-dependent manner.
Conclusions: Driving after an EDWS puts resident physicians/drivers and other road users at avoidable and unnecessary risk. Demonstrating self-reported sleepiness at the beginning of the drive is associated with adverse outcomes has serious implications on the legal accountability for driving when drowsy.
Keywords: driving; drowsiness; residents; safety; shift work; sleepiness.
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