Some additional food for thought:

RimRod notes that you should take breaks. Several studies by the US Military, the US Department of Education and several independent researchers say that you should study for 20-30 minutes at a time, then take a break. Don't do more than three consecutive 20-minute sessions in a row (including 15 minute breaks in between). After three sessions, you start retaining less and less. If you spread your studying for finals over a 4 to 5 day period, you will retain the most information. Some folks have exceptional short-term memory, and they can study an hour before a test and get great grades. If you're not one of these folks, spread out the cramming.