CLEVELAND -- We've all been there. Driving early in the morning or late at night and starting to stare off into the abyss.

Yep, we're talking about drowsy driving.

Just how dangerous is it to get behind the wheel while drowsy and how do you know when to stop?

An easy telltale is when you start yawning or rubbing your eyes repeatedly or when you find yourself blaring the radio or rolling down the window to keep awake.

The National Highway Traffic Safety Administration estimates that at least 100,000 reported crashes a year are caused primarily by drowsy driving. Those have led to more than 1,500 deaths and 71,000 injuries.

Driving drowsy is a lot like drunk driving, officials say. 17 hours of being awake impairs performance equal to having a .05 blood alcohol level. 24 hours of no sleep, that's the same as a .10 BAC, which is above the legal limit in all 50 states.

The national sleep foundation survey suggest half of Americans consistently drive with heavy eyes and about 20 percent admit to falling asleep at the wheel.