By far the most effective formula is:
Laboratory tests showed this approach cuts driver accidents by over 90%. You need to drink two cups of coffee because the caffeine content of each cup of roadside coffee varies widely, from 35 to 80 milligrams. The strength of taste is not related to caffeine content. Energy drinks, available at service stations, can have 75 milligrams of caffeine in a standard dose.
But dosing up with caffeine is a one-off measure. It is not to be repeated. It is a temporary measure and sleepiness will return. The next time you feel tired, take a proper break. Stop the journey.