The impact of self-initiated breaks during drowsy driving.

Data suggest that drowsiness contributes to a large number of motor vehicle crashes, injuries, and deaths each year. Research suggests that taking breaks, examined via forced breaks at set points during simulator or test track driving, can at least momentarily decrease drowsiness and improve subsequent driving performance. In the real world, however, breaks must be initiated by drivers, who also have control over factors such as the break duration and activities engaged during the break. This study examined the impact of self-initiated breaks on driving performance and drowsiness over the course of long overnight drives. Ninety drivers completed a 150-mile highway drive in a driving simulator after a day of partial sleep restriction. They had the opportunity to take breaks at rest areas and could engage in different activities during breaks. An incentive method was used to mimic the motivational conditions of drowsy driving. Driving performance, as measured by lane departure frequency, improved immediately following breaks. Post-break performance began to decline shortly after the break and within 40 minutes performance returned to pre-break levels. Breaks with caffeine were particularly effective in delaying the decline in driving performance. These results indicate that self-initiated breaks, particularly those that involve caffeine consumption, can at least momentarily offset some of the performance impacts of drowsiness. However, breaks may not increase driver alertness and the benefits of breaks are fleeting for most drivers. The findings suggest that breaks may help drowsy drivers, but that they do not completely alleviate the effects of drowsiness.