In the testing literature, the term load testing is usually defined as the process of exercising the system under test by feeding it the largest tasks it can operate with. Load testing is sometimes called volume testing, or longevity/endurance testing.
Keep your taste buds awake, drink an energy drink. This may raise your level of alertness for a reasonable amount of driving time. Suck or munch on an apple, orange, or even a lemon to keep taste buds awake. The more tangy the food item the better. (Pull over somewhere safe before eating anything that you can't just pop in your mouth, however.
To put this in context, prior research has shown that staying awake for 24 hours in a row impairs performance on par with legal intoxication with alcohol (for driving), and six hours of sleep per night for two weeks causes a similar level of impairment as staying awake for 24 hours, Cohen says.