[Falling asleep at the wheel: the chief cause of severe traffic accidents].

All fatal traffic accidents on highways in Bavaria in 1991 have been analyzed. The most frequent single cause for the 204 accidents was falling asleep (24%). A time of day analysis revealed that the highest accidents frequencies could be observed at 6:00 a.m. and 2:00 p.m. In addition an age effect could be observed. The majority of the day accidents were caused by older drivers, while most of the night accidents were caused by younger ones.