It's about that point in the semester when midterms start to kick in and stress increases. At times like this, it's especially important to make sure that you're using your personal learning style to maximize your study effectiveness.
You probably already know whether you're a "morning person", "afternoon person", or "night person", and have figured out that a night person just can't study very effectively early in the day (and vice versa). So step one is to make sure you're working during the time of day you're most alert. But there are other ways that you may naturally learn more easily others. For example, reading is not necessarily the best way for you to study. Many people learn better by hearing the information, or discussing it with others, seeing it in pictures or charts, or with hands-on experience. While you can learn in any of these ways, your brain will naturally absorb information more easily in some formats than others.
We have a Learning Styles Table that outlines the different styles and some study strategies to use based on your style. You can also find more information at North Carolina State's page on learning styles.
Good luck with your studies!