Drowsy and fatigued driving
Driving while tired slows your reactions, weakens your judgment and can end in a microsleep, a few seconds of sleep you may not even notice. At highway speed, a few seconds is long enough to drift across lanes or off the road.
Teens and young adults, shift workers and people on long trips are at higher risk. This topic covers the warning signs and the only reliable fix: sleep.
By the end of this topic you can
- You can recognize the warning signs that you are too tired to drive.
- You can plan trips to avoid driving when you would normally be asleep.
- You can take breaks and share driving on long journeys.
- You can stop safely and rest when you notice drowsiness.
What you need to know and understand
- Fatigue slows your reactions and weakens your attention and judgment. Alcohol makes drowsiness worse, so never drink before driving.
- A microsleep is a brief loss of awareness lasting a few seconds. At 55 mph you can travel more than 100 yards in that time.
- Opening a window, turning up the radio or cooling the car do not reliably keep you awake.
- Caffeine can help for a short time, but it takes a while to work and does not replace sleep.
- Drowsy crashes happen most often between midnight and 6 a.m. and in the late afternoon, when the body clock dips.
- Some medicines, including many allergy and cold remedies, cause drowsiness: read the label.
- Drowsy crashes often involve a driver alone running off the road with no sign of braking, frequently on rural roads and highways.
Signs you are too tired to drive
If you notice any of these, treat it as a warning that you could fall asleep soon. It is not a sign to push on to your destination.
- Frequent yawning or heavy eyelids.
- Drifting from your lane or hitting a rumble strip.
- Missing your exit or not remembering the last few miles.
- Tailgating or missing traffic signs without meaning to.
- Head nodding, restlessness or irritability.
What to do when drowsiness hits
- Find a safe, legal place to stop, such as a rest area or a well-lit parking lot. Do not stop on the shoulder unless it is an emergency.
- Lock the doors and take a short nap of around 20 minutes.
- If you choose to use caffeine, have it before the nap so it starts working as you wake.
- Walk around for a few minutes before setting off again.
- If you still feel tired, do not drive: call someone, swap drivers or stay overnight.
Planning so it does not happen
Get a full night's sleep before a long drive; most teens need more sleep than adults. Avoid driving at times you would normally be asleep, and avoid long drives straight after a night shift, an exam period or a late party.
On long trips, plan regular breaks, roughly every two hours, and share the driving with another licensed driver if you can. Drive with a passenger who will stay awake and talk to you. Many states' graduated licensing rules limit late-night driving for new drivers, partly because of fatigue risk.
Common mistakes
- Relying on loud music or cold air to stay awake: they do not work for long.
- Pushing on because you are close to home: many drowsy crashes happen on familiar roads.
- Driving after a night of little sleep: plan rest before you drive.
- Taking a drowsy medicine before driving: check labels and ask a pharmacist.
- Napping on a freeway shoulder: use a rest area or other safe place.
Test yourself: Drowsy and fatigued driving
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Sources: NHTSA drowsy driving guidance (nhtsa.gov); Alabama Driver Manual chapter 4, highway hypnosis and fatigue (alea.gov). Independent guide, not affiliated with any licensing agency. Always check the latest official rules with your state DMV.