A hangover is as dangerous for drivers as being drunk at the wheel, a study suggests.
The effects of a night's heavy drinking lasted even when the last alcohol had cleared the system, scientists found.
They said hungover drivers made significantly more mistakes in a 20 minute road simulation exercise.
Chris Alford, who led the study at the University of the West of England, said: "Things like their speed of reaction were slowed down. The variability in the way they drive was more erratic.
"You could say their driving was as if they were over the legal limit of alcohol, but of course they didn't have that alcohol on board any more.