In two separate experiments the effects of sleep deprivation and alcohol on simulator driving have been examined. Twenty-four participants operated a driving simulator at five times of day (8 am, 11 am, 2 pm, 5 pm, and 8 pm), after a normal night of sleep and a night of sleep deprivation. In the second study twenty-eight participants operated the simulator across six sessions; two at 12 pm, 6 pm, and 11 pm, after consuming either 0.70 ml/kg body weight alcohol or juice only. To compare the relative effects of sleep loss and alcohol on driving skills, impairments in lateral deviation were expressed as a mean relative performance score. These scores were calculated for each subject using a control score that was based on the normal sleep and no alcohol conditions. The standard deviation of lateral position was the chosen variable, as previous research has shown that this measure is sensitive to differences due to driving experience, driver fatigue, alcohol, and time of day. Twenty-four to 36 hours of sleep loss produced greater impairments in driving skill than alcohol at around the 0.04 percent blood alcohol level. However, the degree of impairment following sleep loss and alcohol was dependent on time of day. (A)
Abstract