The survey with Direct Line found that: 

• One in three drivers overall (31%) admitted “head-nodding” at the wheel – nearly half (45%) of male drivers and one in five (22%) female drivers.
• One in 14 drivers overall (7%) admitted actually “falling asleep” at the wheel – 14% of male drivers and 2% of female drivers.
• Almost half (49%) of drivers admitted driving after less than five hours' sleep – not nearly enough for safe driving. Again, this is more common among men (55%) than women (45%).

Brake added that many drivers aren't aware that if you 'head nod' (also called 'micro-sleeps') you have already nodded off, putting yourself and others in a huge amount of danger. Micro-sleeps can last from two to 30 seconds, meaning that a frighteningly large number of drivers have been temporarily out of control of their vehicles.

The road safety charity highlighted that tired driving kills at least 300 people on UK roads every year – although the actual figure could be much higher as driver tiredness can be hard to prove as a cause of crashes.

Brake is urging drivers to getting a good night's sleep before driving, taking two-hourly breaks, and pulling over somewhere safe as soon as safe to do so, if feeling tired.

Brake also calls on the Government to run more campaigns to raise awareness about the dangers of driving when tired and how to avoid it, as well as calling on them to conduct a review of safe stopping places on motorways, ensuring there are enough to enable drivers to take regular breaks.

Julie Townsend, deputy chief executive, Brake, said: ‘The fact that so many drivers – especially men – have head-nodded at the wheel is horrifying, even more so that many don't recognise this means they have fallen asleep briefly. This survey suggests this is down to many people failing to ensure they always get sufficient sleep before embarking on journeys. We need all drivers to wake up to the fact that 'head nodding' is falling asleep, and can easily lead to catastrophe, but it can, of course be prevented.’ 

The IAM also commented on the research, with director of policy and research Neil Greig saying: 'No one ever suddenly falls asleep at the wheel without some warning "nods" beforehand. Ignoring the signs can be potentially fatal as sleep related crashes commonly involve leaving the road and hitting a solid object at high, and usually survivable, speeds. Be aware that the risk is highest if you drive when you would normally be asleep or after lunch when the body's natural rhythms slow down. 

'Coffee, energy drinks or fresh air offer a quick, but all too often short lived reviver so nothing beats a good night's sleep or a proper break.'