Estimates of the effects of drowsy driving vary depending on how statistics are collected. No research has yielded good news.
The National Highway Traffic Safety Administration (NHTSA) collected police reports from across the United States and determined that falling asleep at the wheel contributes to causing about 100,000 crashes each year. Those wrecks kill more than 1,550 people and leave around 71,000 others injured.
The AAA Foundation for Traffic Safety monitored more 3,500 drivers with in-vehicle cameras for 40 months and found that nodding off was a factor in up to 9.5 percent of crashes. That would make drowsiness three times risker than the NHTSA figures suggest.