In order for your brain to process what you are studying you should have brakes every 25 minutes. During the cramming, you must shut off all devices which can distract you! This is extremely essential due to the brain not being completely focused on the task, while temptations may seduce the brain to do the preferred activity. In the meantime, you may do whatever you want. This will show results especially if you are studying something you dislike.
This is called the Pomodoro Technique. The most eccentric function with this method is that often when you’ve surpassed the time limit of 25 minutes you will find yourself engaged on the given task and therefore you often tend to continue.
Good luck with your studies!