The French has found that drivers who were either drunk or sleepy were at least twice as likely to be responsible for a vehicle accident. That is compared to their well rested or sober counterparts.
Scientists say they know from experimental studies that just four hours of sleep loss will produce as much impairment as a six-pack.
Researchers reporting in the Archives of Internal Medicine say one way for people to reduce their accident risk is to take a nap before they hit the road or drink a few cups of coffee. But, they add, there is no substitute for sleep.