FALLING ASLEEP WHILE DRIVING - ARE DRIVERS AWARE OF PRIOR SLEEPINESS

Falling asleep at the wheel is a common cause of road accidents, but l ittle is known about the extent to which drivers are aware of their sl eepiness prior to such accidents. It is an area with medico-legal impl ications. To simulate this situation 28 healthy young adult experience d drivers, sleep restricted the night before drove for 2 h in the afte rnoon in an interactive real-car simulator incorporating a dull and mo notonous roadway. Lane drifting, typifying sleepy driving, was subdivi ded into minor and major incidents, where the latter was indicative of actually falling asleep. A distinction was made between the subjectiv e perceptions of sleepiness and the likelihood of falling asleep which drivers reported separately. Increasing sleepiness was closely associ ated with an increase in the number of incidents. Major incidents were preceded by self-awareness of sleepiness well beforehand and typicall y, subjects reached the stage of fighting sleep when these incidents h appened. Whilst the perceived likelihood of falling asleep was highly correlated with increasing sleepiness, some subjects failed to appreci ate that extreme sleepiness is accompanied by a high likelihood of fal ling asleep. It was not possible for our subjects to fall asleep at th e wheel and have an ''accident'' without experiencing a sustained peri od of increasing sleepiness, of which they were quite aware. There is a need to educate at least some drivers that extreme sleepiness is ver y likely to lead to falling asleep and a high accident risk.