1. Go for a run: I know exercise probably is the LAST thing you wanna do right now but trust me, there is something unexplainable about exercising outside. Trust me, running will help you relieve stress, and the endorphins will improve your mood and concentration.
2. Take a shower: The hot steam will help relax your muscles, and will also help with stress relief. Besides, when is taking a shower not a good idea??
3. Cook/Bake: Let's be honest, you're probably eating take out and/or ramen, and the last thing you think you have time for is make something somewhat edible for yourself. Here's an amazing recipe for cake that actually takes no time to bake with ingredients you probably have on hand anyways.
4. Go grocery shopping: Let's be honest, you probably have next to nothing to eat anyway. Take it from someone with experience, eating popcorn as a meal substitute isn't the hottest idea in the world.
5. Pamper Yourself: By this, I mean take some time out of studying to treat yourself. I know for me when I need a break, I go and put on eyeliner because it's something that makes me look more awake and looks nice on my eyes, which really increases my confidence. It's stupid I know, but trust me, it's these little things that'll help you push through.