It has probably happened to you: you're out driving late at night or on a long road trip, and your head starts to nod. You start to struggle to stay awake, drifting back and forth in your lane, until you decide to pull off the road and designate a different driver or take a nap.
If you've been in this situation, you have hopefully always been able to catch yourself before you fell completely asleep and got into a car accident. Many people, however, are not that lucky. That's why several automakers have begun experimenting with technology aimed at preventing drowsy driving accidents.








