Crashes and Fatalities
Sleepiness can result in crashes any time of the day or night, but three factors are most commonly associated with drowsy-driving crashes.
- Occur most frequently between midnight and 6 a.m., or in the late afternoon. At both times of the day, people experience dips in their circadian rhythm—the human body’s internal clock that regulates sleep;
- Often involve only a single driver (and no passengers) running off the road at a high rate of speed with no evidence of braking; and
- Frequently occur on rural roads and highways.
Precise numbers of drowsy-driving crashes, injuries and fatalities are had to nail down
Unfortunately, determining a precise number of drowsy-driving crashes, injuries, and fatalities is not yet possible. Crash investigators can look for clues that drowsiness contributed to a crash, but these clues are not always identifiable or conclusive.
NHTSA’s census of fatal crashes and estimate of traffic-related crashes and injuries rely on police and hospital reports to determine the incidence of drowsy-driving crashes. NHTSA estimates that in 2015, 90,000 police-reported crashes involved drowsy drivers. These crashes led to an estimated 41,000 people injured and more than 800 deaths. But there is broad agreement across the traffic safety, sleep science, and public health communities that this is an underestimate of the impact of drowsy driving.