A hangover following a night of heavy drinking can impair driving performance as much as driving under the influence of alcohol, according to new research by Associate Professor Chris Alford of the University of the West of England and Assistant Professor Joris Verster of Utrecht University.
The complementary studies were presented at the Australasian Professional Society on Alcohol and other Drugs (APSAD) 2013 Conference. They recommend that drivers should be warned that the effects of heavy drinking last longer than a measurable blood alcohol concentration (BAC) and that hangover immunity is largely a myth.
In Professor Alford's UK study, participants who had been drinking the night before undertook a 20-minute simulation of driving in a mixed urban and rural setting with hazards such as pedestrians, which could represent a typical commute to work.
Significant increases in speed variability, reaction time, driving errors and deviation from driving position were recorded when the participants were hung-over.
Professor Alford said the finding that driving performance was adversely affected by hangovers should be incorporated into driver safety campaigns.
"This was a naturalistic design of study, aiming to better reflect what happens in real life when people go to work the next day after drinking. The significant impairments seen here, after a relatively short driving duration reflecting a typical commute to work and using a more mentally demanding driving environment, represent a new finding.
"This simulation represented a situation many people can relate to. They may already be aware of not driving home after a night out drinking, but we also need to advise them to plan for the next day so they won't be driving to work impaired," he said.
In the larger, complementary Dutch study, healthy volunteers participated in simulated one hour motorway driving tests the night after a drinking session averaging about ten alcoholic drinks.
Compared to the same tests after a night of not drinking, the results showed a hangover could significantly increase the number of lapses in attention and driving course deviations or weaving. The tests were performed after the participants' BAC had returned to zero, although their level of driving impairment was similar to being over the alcohol limit for driving in Holland.
The types of hangover symptoms people experience include thirst and dehydration, drowsiness and fatigue, headache and problems concentrating, according to other research. While some people claim to be immune to developing a hangover, a Canadian study of almost 800 university students suggests that the vast majority of drinkers are susceptible and the impact is largely related to the degree of alcohol intoxication.