A quarter of crashes on our main roads, causing death or serious injury, are tiredness-related. Crashes caused by drivers falling asleep tend to be high-speed crashes, because drivers do not brake. Even if tired drivers do not fall asleep behind the wheel, they still pose a danger. Too little sleep radically affects your ability to drive safely, increasing reaction times, reducing attention the ability to control the vehicle. Drivers should go no more than two hours before taking a break. Research has found driving performance deteriorates after this length of time, as you become less able to concentrate and slower to react to hazards.
BRAKE recommend drivers take a minimum of 15 minutes break at least every two hours.