The effects of a nap opportunity in quiet and noisy environments on driving performance.

While napping has previously been shown to alleviate the effects of sleep loss, before advocating the use of naps in transport accident campaigns it is necessary to consider whether a nap opportunity in a noisy uncomfortable environment can produce the same benefits as a nap opportunity in conditions that are conducive to sleep. To examine this, eight participants drove a driving simulator for 50 min at 11:00h on three different test days. The simulator used has previously been found to be sensitive to the effects of sleep loss, alcohol consumption, and time of day. All three sessions were conducted after one night of sleep loss. Prior to driving during each session the participants either had a 60 min nap opportunity in a quiet or noisy environment, or no nap opportunity. Driving performance and reaction time while driving were measured, as were subjective sleepiness and ratings of sleep quality. No significant benefits of nap opportunities on driving performance were found. Levels of subjective sleepiness were not affected by the nap opportunity condition; however, sleep was rated as more refreshing and restful after a nap in a quiet environment compared to noisy environment. The measures of effect size reported suggest further research is required to unequivocally test the effects of nap opportunities on driving ability.