A Case-Crossover Study of Sleep and Work Hours and the Risk of Road Traffic Accidents

Abstract

Sleepiness, prolonged wakefulness, and extended work hours have been associated with increased risk of injuries and road accidents. The authors' objective was to study the relation between those factors and road accidents using a case-crossover design, effective in estimating the risk of acute events associated with transient, short effect exposures. Five hundred seventy-four injured drivers presenting for care after road accidents to the Emergency Room of Udine, Italy, were enrolled in the study from March 2007 to March 2008. Sleep, work, and driving patterns in the 48 h before the accident were assessed through an interview. The relative risk (RR) of accident associated with each exposure was estimated using the case-crossover matched pair interval approach. Sleeping > or = 11 h daily was associated with a decrease of the RR, as was sleeping less than usual. Being awake > or = 16 h and, possibly, working > 12 h daily were associated with increases in the RR. Extended work hours and prolonged wakefulness increase the risk of road accidents and suggest that awareness should be raised among drivers. The findings regarding acute sleep amount are less clear, possibly due to an effect of chronic sleep loss.