A new study has revealed that in the past year one in eight motorists have put themselves and other road users at risk by falling asleep while driving.
The period for which they dozed off ranged from two to 30 seconds, while many did so unknowingly, risking death, injury, arrest and higher van insurance premiums.
The survey, carried out jointly by charity Brake and Cambridge Weight Plan, found that a quarter of drivers get behind the wheel even though they are already tired.
A further 29% admit they carry on driving even after they notice the initial signs of sleepiness.
Motorists who feel too drowsy should stop at a safe place and rest, but the study shows nearly nine in 10 do not follow this advice.
Out of the 1,000 drivers polled, 13% said they were suffering from a disorder called sleep apnoea. The condition can lead to fatigue and daytime sleepiness, with sufferers running the risk of falling asleep suddenly.
© Press Association 2011