Sleepy drivers with less than four hours of sleep are 11 times more likely to experience a car crash than drivers with 7 hours of sleep the night before. Twenty-one percent of all fatal highway crashes involve drowsy drivers. Drowsy driving reduces alertness and attention the same way as being drunk or texting does. Know the signs of drowsy driving. These include lane swerving, falling asleep while stopped in traffic or at a traffic light, sudden braking (when the driver realizes he/she has fallen asleep and awakens in fright), slow reaction time, and poor decision making. There are many ways to increase alertness, but the best way is to pull over and take a nap.