Acute and hang-over effects of alcohol on simulated driving performance

The aim was to study hang-over effects from alcohol in simulated driving. The driving task was to negotiate 20 km in as short time as possible. The road had many curves, horizontal and vertical, with ice friction at irregular intervals. 24 healthy volunteers, aged 22-46, with valid driving licenses, all screened as moderate drinkers, participated as subjects in a repeated measurements design. In the acute intoxicated state (average BAC 150 mg%), driving performance was severely impaired. Performance was also impaired, but to a much lesser degree, in the morning after the alcohol consumption when average BAC was just below 40 mg%. Later during the day no significant differences were demonstrated. After another night's sleep, all effects were gone. An issue raised in a previous study on hang-over effects, whether the subjects were treated exactly alike in the hang-over and the control conditions the night before testing (with the exception for the alcohol consumption in the first case), that is attended a party and stayed overnight at the research institute in both conditions, or whether they did so only in the hang-over condition, did not seem to matter for the estimated hang-over effect.