A tired driver is a deadly driver. He killed himself and injured all 21 passengers on the bus. According to a spokesperson for the Alabama State Troopers, investigating officers suspect that fatigue may have played a significant role in the crash.
Drowsiness also plays a role in crashes attributed to other causes.
Clinical studies show that sleep deprivation and fatigue make such attention lapses more likely to occur. Maycock, G. Driver Sleepiness as a Factor in Car and HGV Accidents . Report No. 169 for Transport Research Laboratory. Pack et al. Having Fallen Asleep .