Well if I’m understanding this right,
Person reason: For example if they have issues sleeping like insomnia or just have their sleeping off track.
Academic reason: Could be because they’re studying or they’re worrying over a test that is due the next day and they want good grades. It could also be stress induced. Maybe they have too much on their plate academically.
Not a good reason: They’re staying up watching movies or a tv show. Maybe texting or talking on the phone as well. Something they could do in their spare time but they choose to do it at night.
I hope that answers your question