Drowsy driving: more dangerous than you think

• Driving while sleepy: about 8 times higher risk of an injury crash.
• Less than 5 hours of sleep: about 2.7 times higher risk.
• Driving between 2 and 5 a.m.: about 5.6 times higher risk.
• Eliminating drowsy driving could prevent about 19% of injury crashes.

What the research shows

Case-control study. In New Zealand, researchers compared drivers involved in crashes causing injury or death with randomly selected drivers on the road. Drivers who rated themselves as sleepy had about 8 times the risk of an injury crash. Driving after less than 5 hours of sleep in the past 24 hours was linked to 2.7 times the risk, and driving between 2 and 5 a.m. to 5.6 times the risk. The authors estimated that eliminating these factors could reduce injury crashes by up to 19% (Connor et al., 2002).

Shift work and sleep apnea. Shift workers (Kecklund & Axelsson, 2016) and people with untreated sleep apnea (Benjafield et al., 2019) are at higher risk of drowsy-driving crashes. The National Highway Traffic Safety Administration estimates that drowsy driving causes tens of thousands of crashes in the U.S. each year.

Rules of the road

• Get 7 or more hours of sleep before a long drive.
• Avoid driving between midnight and 6 a.m. when possible.
• Take a break every 2 hours on long trips.
• If you feel drowsy, pull over somewhere safe and nap for 15 to 20 minutes.
• Do not drink alcohol before driving, even small amounts.
• Turning up the radio or opening the window does not work.