Objective The aim of this study was to compare performance measures after acute alcohol consumption (intoxication) with the performance the day after a normal night’s drinking (hangover).

Methods Eighty-four social drinkers took part in two studies that followed a counterbalanced repeated measure design. Fifteen men and 33 women were tested the morning (09:00, 11:00 or 13:00 h) following normal/usual alcohol consumption and the morning after no alcohol consumption; the order of testing was counterbalanced. In a second study, 36 participants (18 men and 18 women) were tested after receiving alcohol to attain a blood alcohol concentration of 0.08%, and after no alcohol administration, the order of testing was counterbalanced. In both studies, participants completed a task battery of memory, reaction time and attention tasks.

Results Alcohol had no effect on the free recall task and the spatial attention task. Alcohol consumption, either acute or the next day, significantly affected reaction time, divided attention, selective attention and Stroop interference. The impairments during intoxication and hangover were of comparable magnitude. Performance on tasks of delayed recognition and irregular interstimulus reaction time was worse during hangover when compared with intoxication.

Conclusion It is evident that awareness needs to be raised that performance the morning after alcohol consumption is at the same level if not worse than when participants are at the legal limit for driving (0.08% blood alcohol concentration).