Two million exhausted drivers a year falling asleep at the wheel

The danger is fuelled by too many motorists relying on safety myths to stave off tiredness - such as opening the window for a blast of cool air or cranking up the volume on the radio.

Advice from the Department for Transport is to take a break every two hours on long journeys and pull over for a nap if tiredness grows.

Scroll down for more...

But today's survey from road safety charity Brake, conducted with the breakdown firm Green Flag, reveals a 'deadly ignorance' about safe strategies to stay alert.

In all 2.3million motorists - 7 per cent of the country's drivers - admit they fell asleep while driving in the last 12 months.

And 133,000 say it happened ten times or more.

The figures, which have already led to calls for a clampdown on those who ignore official advice on tiredness, come as police are looking to develop hand-held devices to test for driving impairment through fatigue, old age or drugs.

A fifth of motorway crashes, which most commonly happen between midnight and 6am or 2pm and 4pm, are because of fatigue.

Tiredness is estimated to be responsible for more than 300 deaths on the roads a year.

The survey of 1,000 drivers found that 78 per cent try futile methods to combat the problem rather than stop for a nap.

Just 21 per cent said they would stop for a snooze but 68 per cent would open a window and 50 per cent listen to the radio, CD or tape.

More than two thirds - 71 per cent - claim to have a good night's sleep before a long journey and to take regular breaks.

Scroll down for more...

Four out of 10 have a drink containing caffeine to give them a boost.

Brake's head of education Jools Townsend said: "It is shocking that drivers are so ignorant about how to prevent tiredness on the road.

"It's crucial that drivers planning long journeys are aware of the dangers of driving tired and know how to avoid it."

Green Flag's Abi Clark said: "Drivers can't just open a window or crank the music up to keep awake - they need to ensure they have a break every two hours when on a long journey and stop and take a nap if they feel tired."

More than four out of ten of tired drivers say they would stop earlier if possible.

But the Institute of Advanced Motorists' Trust says high prices at motorway service stations could tempt drivers to postpone rest breaks.

Director Bert Morris said: 'Many drivers choose to boycott highpriced service areas.

"When that happens-safety is compromised."

The call for a clampdown was backed by the widow of Steve Dunn, a train driver killed at Selby in 2001 when dozing driver Gary Hart careered off the M62 in Yorkshire and on to rail tracks.

Ten people were killed. Hart was jailed for five years.

Mary Dunn said: "Too many people think that driving while tired is harmless without realising that they are in charge of a lethal weapon, capable of causing a major catastrophe like in Selby."