Sleep deprivation is one the biggest factors in car crashes in the U.S. The National Highway Traffic Safety Administration says drowsy driving kills more than 1,500 Americans each year.

There's little time for rest for truck driver Gregory Sligh; five days a week, 14-hours a day he's on the road.

“It gets pretty tiresome sometimes you know. You travel the same road day after day,” he said.

Michael Harlon says he's experienced his share of nodding off at the wheel. Nearly seven days a week he clocks in hundreds of miles carrying cargo from state to state.

“The worse thing is, it's scary when I start doing the head nod,” he said.

Both drivers say with only an average six hours of sleep a day staying alert on the road requires a lot of help. Seventeen percent of all deadly car crashes involve big rigs. In nearly all those accidents sleep deprivation was the major factor.

Dr. Amy Blanchard of MCGHealth Sleep Disorder Center says driving while drowsy is as dangerous as driving under the influence. There are clear signs you can look for to tell if you're sleep deprived.

“Falling asleep in meetings, inability to feel refreshed when you wake up in the morning, hitting the snooze button on the alarm clock,” she said.

She suggests drivers get up to 10 hours of sleep before hitting the road. Make sure to lay off medications before driving. If you feel tired, make sure to go to a rest stop to take a nap or a walk.