IMO avoid energy drinks and coffee. They will make you hyperactive for awhile but their effect is short-term, you will end up feeling even more tired.
I would exercise. It's something that makes you feel more awake, naturally. It doesn't have to be anything extra heavy, even a 30-min jog is enough. You get some fresh air and hopefully you will think something else than school (although it's great time to review things while exercising). You will feel like a new man after that. Heck, I often go to gym
to study! People do look me in a strange way when I'm reading something while running on a treadmill though
Take a nap. Reading a book, especially something like biology can be extremely boring and makes you fall asleep. Instead of trying to read while your brain is basically asleep, take a short nap. 30 minutes maximum IMO. Longer than that will affect your night sleep but a good half an hour gives you some energy to concentrate on studying.
Make concept maps. They are VERY easy to understand and while making them, you have to understand what you are reading. This works extremely well if there is something you don't really get at all. Great way to squeeze pages and pages of information into one sheet of paper. Personally, I use
CMap. Right before the holidays, I had to do a physics assignment. I chose dark energy as my subject and honestly, I had no idea what it was before I started. It was about 20-page article with lots of new words and concepts. Skimmed through it couple of times without understanding much of it. Then, I decided to turn it into a concept map. Sure it took awhile to go through the text and pick the most important words but in the end, I really understood what it was about. Just reading and reading isn't enough.
That is what I do. No guarantee that it will work for anyone else but I've found it to be good