OBJECTIVES: Extended duration (≥24 h) work shifts (EDWS) 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 pre-drive self -reported sleepiness was evaluated in medical residents after EDWS.
METHODS: Sixteen resident physicians (10F;29.2±2.0y) 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. Subjective sleepiness (Karolinska Sleepiness Scale; KSS) and objective drowsiness were captured using a time-stamped, hand held device and infra-red reflectance oculography.
RESULTS: Subjective sleepiness and objective indices of drowsiness were positively correlated, and both were elevated following EDWS. Compared to the commute to work, EDWS 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. EDWS 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 pre-drive KSS level, and in a dose-dependent manner.
CONCLUSIONS: Driving after 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.