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.
Do not drive distracted. Turn off your cell phone or give it to a passenger, make sure your makeup is okay before you leave, read your newspaper before you leave, set your radio dial before you leave. In other words, don't let go of the steering wheel to eat, drink, or mess with anything. If the phone rings when you're driving, either have a passenger answer it for you, or pull over to the side of the road and answer it.