Falling asleep at the wheel: Causes and consequences

Previous research has shown that 1 - 6 % of all car crashes and 3 -15 % of fatal crashes are caused by fatigue or sleep. To investigate possible contributing factors a questionnaire study was carried out among 4448 drivers who had been involved in a crash. Fatigue or sleep was a contributing factor in 1.3 % of the crashes. Twenty-two per cent of the drivers had fallen asleep during the last 12 months, and 4.3 % of those incidents resulted in a crash. More male than female drivers fall asleep at the wheel, and more young than elderly drivers. Forty per cent of the sleep or fatigue related crashes were caused by drivers with sleeping problems. Falling asleep while driving is more likely to occur in good and/or monotonous driving conditions. Most drivers who fall asleep feel tired in advance, but continue driving despite this. Drivers who get tired report trying various measures to keep awake, mostly without effect.