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.
Go to bed early. More time asleep in bed equals less chances of falling asleep at work. What you can do to stay awake is you can eat a little of sugar or salt. Always give your face a little hit once in a while it will alert your body to stay awake and you can never sleep with pain.