You may believe that you can stop yourself from falling asleep when you are driving drowsy, but you can't. You may not even know you've dozed off. This is more likely to happen if you are sleep-deprived, driving long distances without rest breaks, traveling at night, driving alone, riding long rural highways, taking medicine that causes sleepiness, or drinking alcohol.

Try these tips from the National Highway Traffic Safety Administration:

• Never drink and drive. Alcohol reduces your driving ability and makes tiredness worse. It's also illegal to drive under the influence of alcohol.
• If possible, don't drive long distances alone. If you have a companion on your drive, you'll have someone to talk with. Plus you can take turns driving.
• Get enough shut-eye. You're more likely to nod off at the wheel if you have slept for less than 8 hours the night before.
• Don't begin a trip so late that you're driving when you usually sleep. Start when you're fresh and alert.
• Watch your posture. Hold your head up and don't slouch.
• Take a break at least every 2 hours. Stop in a place that is safe and well-populated to walk around and stretch.
• Have 2 cups of a caffeinated drink like coffee, if you can have caffeine.

You may be about to doze off if you:

• Can't remember the last few miles you drove.
• Have wandering or disconnected thoughts.
• Have trouble focusing or keeping your eyes open.
• Have trouble keeping your head up.
• Drift from your lane or hit a rumble strip.
• Yawn repeatedly.

In these cases, it's very important to pull over to a safe place. Turn off your car, lock your doors, and nap for 15 to 20 minutes in a busy, well-lit rest area or truck stop. You'll wake up refreshed and ready to reach your destination safely.