Reading is a passive activity. When you get tired or bored it’s easy to drift off, for your eyes to glaze over and to catch yourself re-reading the same material over and over again. Of course, reading plays an important part of revision, but active revision exercises engage your brain, forcing you to interact with the material.
It’s also easy to hide behind reading – convincing yourself that you’re learning, when really the information just washes over you. Do your mind a favour, give it something more stimulating to do.