If you feel tired while driving, pull over and stop the car as soon as you can safely do so. Drowsy driving can be as dangerous as driving while intoxicated. If you know in advance that you may need to drive while tired, it is best to arrange to ride with a friend or coworker, take public transportation, or reschedule your drive. Warning signs of drowsy driving include difficulty focusing, eyelids that feel heavy, not remembering the last few minutes or miles, frequent blinking or yawning, and drifting across lanes. A 20-minute nap can help improve alertness and safe driving ability. Caffeine may also help, but it may be less effective if you are very sleep deprived or if you regularly use caffeine. Cold air, food, non-caffeinated beverages, and listening to music have not been proven to prevent drowsy driving.