Two studies by researchers from Utrecht University in the Netherlands and University of the West of England in the UK presented a series of driving tests that mimicked highway driving. The individuals had an average of 10 alcoholic drinks the night before.
The subjects did not have any alcohol present in their blood but still showed signs of increased weaving and decreased ability to pay attention on the road. The results were comparable to those of someone with a blood alcohol concentration of .05.
A second study showed researchers that the drivers experienced delayed reaction times and were driving at inconsistent speeds when presented with a simulation of stop-and-go traffic after a night of drinking.
When people experience a hangover, they are having a short-term withdrawal from alcohol, which combined with sleep deprivation and dehydration can make driving dangerous.
Since there is no real way to measure how hungover someone is, researchers are hoping to create awareness about the risks of driving after a night of drinking.