Do you know why studying in short but frequent sessions are better than studying straight for 5 hours to 8 hours? It is because those repeatedly brief burst of concentration are similar on how our brain works. The human brain after working needs to rest to synthesize the information it gets.

And so, avoid stressing out yourself to study the whole day because you are putting to much pressure on your mind. Instead, allot an in between short break or mind relaxation to give time for your brain to absorb what you have read.  Sipping a cup of tea or a cup of coffee once in a while when you are reviewing for your exam is actually helpful to your mind.