Caffeine should not be a substitute for sleep, however. You should also be aware that it takes about 30 minutes for caffeine to enter your bloodstream and the effects last about two to three hours. Although caffeine can make you alert, it's not enough to keep you alert all by itself. Avoid becoming too comfortable in your car. Studies suggest that physical discomfort may keep sleepy drivers awake.
Many studies show that exposure to bright light reduces sleepiness.
Travel with a passenger. A passenger can look out for the driver, and make sure he or she is not suffering from fatigue. In most situations, a passenger can also take over the driving if the driver gets tired. You should know that there is no evidence that getting out of the car and walking around, listening to the radio, or opening a car window reduces sleepiness. You have trouble focusing and keeping your eyes open.