Transcript for Nationwide Epidemic: Exhausted Drivers
tonight, and to an urgent call to action about a nationwide epidemic. Exhausted drivers falling asleep at the wheel. You're about to see what can happen after nodding off for just two seconds. Here's ABC's David Kerley. Reporter: Watch. This driver is nodding off, drifting out of his lane, rear-ending another car. It can happen in just two seconds. Tonight, the national transportation safety board says we need to wake up to drowsy driving dangers do Americans underestimate how tired they are sometimes? One of the biggest part of the problem. Humans are just horribly inaccurate if. We have to self-diagnose fatigue, we are usually way off. Reporter: 40% of drivers admit falling asleep at the wheel. Losing two hours of sleep just one night can cut your attention reaction time, decision-making by 20% to 50%. All that adds up to one of the most underreported problems on the road. One study suggests that 20%, 1 out of every 5 accidents, involves a tired driver. At Virginia tech's test track, researchers are assessing drivers like me for alertness, signs of fatigue. Do I notice a box falling out of a truck. Whoa, bhwhoa, whoa. Or a pedestrian on the side of a road. Do you know what color hat he was wearing? Reporter: Red. They're testing cameras, looking for signs of a lack of sleep. A problem that only worsens as you try to fight off nodding off. Tonight, the best advice? Stay out of your car if you haven't had enough sleep. David Kerley, ABC news, Washington.
This transcript has been automatically generated and may not be 100% accurate.