Fatigue is a major contributor to automobile accidents and this may be because as many as 15.8% of drivers may be driving while being severely fatigued.
How do they get so fatigued? One pattern that we often see is that instead of prioritizing sleep on the night before a long drive, people prioritize the driving. Upwards of 76% of drivers on long journeys (over 600 kms) shorten their sleep to get on the road early and the longer they drive the worse they drive.
Driving simulator studies show that fatigued drivers are like drunk drivers; they have a hard time maintaining correct speeds and they weave around on the road. Fatigued people also react more slowly than well-rested people. This means that if you are fatigued, you may drive too fast and react too slowly to avoid a rear-end collision. It also means that you might drift into oncoming traffic and not be a able to steer out of the way quickly enough to avoid a head on collision.
The lesson here is that if you are a driver and especially if you are planning a long drive during this year’s summer vacation, you need to get between 7 and 8 hours of good quality, uninterrupted, night time sleep before you jump behind the wheel.
 See for examples:
(A) Horne, J., & Reyner, L. (1995). Sleep related vehicle accidents. British Medical Journal, 4, 565-567.
(B) Philip, P., Vervialle, F., Le Breton, P., Tailliard, J., & Horne, J. (2001). Fatigue, alcohol and traffic accidents in France. British Medical Journal, 322, 829-830.
 Philip, P., Taillard, J., Klein, E., Sagaspe, P., Charles, A., Davies, W., Guilleminault, C., & Bioulac, B. (2003). Effect of fatigue on performance measured by a driving simulator in automobile drivers. Journal of Psychosomatic Research, 55, 197-200.
 See for examples:
(A) Arnedt, J.T., Wilde, G., Munt, P., & MacLean, A. (2001). How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task? Accident Analysis and Prevention, 33, 327-344.
(B) Ware, J.C., Risser, M., Manser, T., & Karlson, K. (2006). Medical resident driving simulator performance following a night on call. Behavioral Sleep Medicine, 4(1), 1-12.