Dehydrated drivers as bad as drunk drivers

Driving while dehydrated is just as bad as drink driving, a university study has concluded.

Researchers at Loughborough University found that dehydrated drivers make the same number of mistakes as drink drivers, with even mild dehydration said to be the equivalent of being over the limit.

As part of the study, a range of tests were carried out over two days on male drivers using a laboratory-based driving simulator. During the normal hydration test there were 47 driving incidents, but when the men were dehydrated that number more than doubled to 101. These errors included lane drifting, late braking and touching or crossing the rumble strip or lane line.

In fact, the number of errors made by dehydrated drivers was similar to that expected of someone driving under the influence of drugs or with a blood alcohol content of 0.08%, the current UK legal driving limit.

Professor Ron Maughan, professor of sport and exercise nutrition at Loughborough University who led the study, said: “We all deplore drink driving, but we don’t usually think about the effects of other things that affect our driving skills, and one of those is not drinking and dehydration. There is no question that driving while under the influence of drink or drugs increases the risk of accidents, but our findings highlight an unrecognised danger and suggest that drivers should be encouraged to make sure they are properly hydrated.”

The European Food Safety Authority recommends that women should drink 1.6 litres (eight glasses) of fluid per day and men two litres (ten glasses).

We need water because we are water — it makes up 78 per cent of our brains and two-thirds of the weight of our body.

The research was published in the medical journal Physiology and Behaviour.