Sleepiness and hazard perception while driving

Young drivers are involved disproportionately in serious vehicle crashes, and are involved disproportionately in sleepiness-related crashes. Specific difficulties in perceiving road hazards, and further impairment of this skill when sleepy, may contribute to this problem in young and inexperienced drivers. Perception, and response, to potential driving hazards is typically better in experienced drivers than in inexperienced drivers. However, the relationship between driver experience and sleepiness is not known. A sample of 34 young, and inexperienced, drivers (aged 17-24 years, with less than three years driving experience) and 33 older, and experienced, drivers (aged 28-36 years, with at least ten years driving experience) completed a video-based hazard perception task, in which they were instructed to anticipate a range of genuine traffic conflicts filmed locally. Their average response time to the traffic conflicts was calculated. Drivers were either tested at a time of increased sleepiness (3am) or at a point of decreased sleepiness (10am). As expected, the young, inexperienced drivers were significantly slower at identifying hazards than were the older, experienced drivers. While no overall effect of sleepiness on hazard perception was found, inexperienced drivers were slower on this measure at night. It appears that the hazard perception skills of the older, more experienced, drivers were relatively unaffected by mild increases in sleepiness while the hazard perception skills of the younger, inexperienced drivers, were significantly slowed by a mild increase in sleepiness. The results may explain the increased risk of driving while sleepy for young adult drivers. Sleepiness impairs elements of driving performance that are critical to safe driving, including hazard perception.

Type: Research and Analysis Report

Sub Type: Grant

Author(s): Simon Smith; Mark Horswill; Brooke Chambers; Mark Wetton

Topics: Fatigue

Publication Date: 06/04/09