Tired drivers can be as dangerous as drunk drivers, according to new research.
An exclusive test carried out by What Car? in simulators at the Transport Research Laboratory compared the ability of a tired driver with a drunk driver.
Two drivers were put through a series of tests.
Driver 1 was not allowed to sleep until 3am and Driver 2 consumed 12 units of alcohol over the course of a night.
They were both then asked to negotiate a similar route that included motorways and A-roads.
When 25% over the legal limit, the drunk driver's ability to hold a steady distance from a car in front dropped by 25%, while his ability to keep to the centre of a lane dropped 23%.
At 2am, the sleep-deprived driver was 39% less able to maintain a steady distance from a car in front, and his capacity to drive within a lane suffered by 37%.
The drink driver did prove to be the worse driver overall.
When twice over the legal limit he was 49% worse at maintaining a steady distance and 42%worse at keeping to his lane.
Researchers also found that 40% of drivers admit to falling asleep at the wheel.
Steve Fowler, What Car? group editor, said: ‘It’s not surprising to learn that drink seriously affects driving ability, but it is worrying to discover that a sober person’s driving ability can suffer more when they are tired.
‘Our message to drivers is simple: don't drink and drive and don’t drive tired. If you are feeling drowsy, pull over in a safe location, lock the doors and have a nap – better to arrive late than not at all.'
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