Warning signs
Frequent yawning, drifting in the lane, missing exits, and trouble remembering the last few miles are all early warning signs. By the time you find yourself jerking awake, you have already had a microsleep — a momentary loss of consciousness — at highway speed.
What does not work
Cool air, loud music, caffeine, and rolling down the window all delay sleep but do not prevent it. Caffeine takes about 20 to 30 minutes to take effect. If you are already drowsy, that is far too long.
What does work
Pull over to a safe rest area or parking lot. Take a 20-minute nap. If a passenger is licensed, switch drivers. If not, sleep until you are alert before continuing. The lost time is a tiny fraction of the time a crash would cost you.
Plan ahead for long drives
Get a full night of sleep before a long drive. Schedule a 10-minute break every two hours. Avoid driving between midnight and 6 a.m. when your body's circadian rhythm is at its lowest alertness.