Exercise!! I know, it seems absolutely bizarre that I would exert more energy to create .. more energy. But I honestly, and whole heartedly believe in it. Ten minutes on an elliptical, or any exercise machine in your home (or even just jump roping, yoga or jogging in place) will keep your eyes awake for another good two hours. It's like a good shot of caffeine in your bones. So, after discovering this, I convinced my mom to buy one of those stationary bikes, because I like reading while exercising. And, I sit there and burn off about 100 calories in a shot. It's a nice, relaxing break from my studying (hello procrastination).