I wanted to share another great app– Tide https://tide.fm/en_US/. Tide is an app focusing on sleep, meditation, relax and focus. It has mini breathing sessions, but what I like the most is that they have a ton of free white noise tunes to listen to as you meditate or study.
Also, the app is free which is great! It does have in-app purchases but I personally have never bought anything and find there to be more than enough content for my intended uses which is breathing exercises and studying. Let me know if anyone checks it out and what you think?