Don't get too comfortable. Put yourself into a situation where your mind is alert. Use the library. Libraries are designed for learning. Entering a library is a signal to your body to quiet the mind and get to work.
Most students can get more done in a shorter time at the library.
Set up study groups. A study group doesn't take the place of individual study, but it forces you to articulate concepts and makes a review more fun and productive. Also, it helps keep your review on schedule and helps you to avoid procrastination. If this happens too often, perhaps you need to find a different study time or place. Agree with living mates about study time.