Alcohol, Sleep Deprivation, and Driving Speed Effects upon Control Use during Driving

An instrumented car was driven through a simple, short, pylon-defined, serpentine course on each of four experimental days, on four consecutive trials each day, after ingestion of an alcohol or a placebo beverage, and after a night of normal sleep or following 29 hours of sleep deprivation. In general, alcohol significantly increased control-use rate, whereas sleep deprivation tended to have the opposite effect in that it significantly decreased the effects of alcohol on coarse-steering reversal rates. Furthermore, the magnitude of alcohol effects upon coarse-steering reversal rates was directly and significantly related to the extraversion of the drivers. It was concluded that, if control-use behavior were to serve as an index of alcohol-associated impairment, the influence of sleep deprivation and individual differences (e.g., extraversion) would have to be taken into consideration.