Effects of moderate sleep deprivation and low-dose alcohol on driving simulator performance and perception in young men.

STUDY OBJECTIVE: To determine the combined effects of sleep restriction and low-dose alcohol on driving simulator performance, EEG, and subjective levels of sleepiness and performance in the mid-afternoon.

DESIGN: Repeated measures with 4 experimental conditions. Normal sleep without alcohol, sleep restriction alone (4 hours) and sleep restriction in combination with 2 different low blood alcohol concentrations (0.025 g/dL and 0.035 g/dL).

SETTING: Sleep Laboratory, Adelaide Institute for Sleep Health.

PARTICIPANTS: Twenty-one healthy young men, aged 18-30 years, mean (+/-SD) = 22.5(+/-3.7) years, BMI = 25(+/-6.7) kg/m2; all had normal sleep patterns and were free of sleep disorders.

MEASUREMENTS: Participants completed a 70-minute simulated driving session, commencing at 14:00. Driving parameters included steering deviation, braking reaction time, and number of collisions. Alpha and theta EEG activity and subjective driving performance and sleepiness were also measured throughout the driving task.

RESULTS: All measures were significantly affected by time. Steering deviation increased significantly when sleep restriction was combined with the higher dose alcohol. This combination also resulted in a significant increase in alpha/theta EEG activity throughout the drive, as well as greater subjective sleepiness and negative driving performance ratings compared to control or sleep restriction alone.

DISCUSSION: These data indicate that combining low-dose alcohol with moderate sleep restriction results in significant decrements to subjective alertness and performance as well as to some driving performance and EEG parameters. This highlights the potential risks of driving after consumption of low and legal doses of alcohol when also sleep restricted.