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.
Numerous other, less credible accounts abound, including one of a British woman in 1977 who won a competition to continuously rock in a rocking chair (presumably by a landslide) by doing so for 18 days. Overall, the jury is out on just how long a human could ever stay awake, but perhaps that's a good thing.