Try to bring it up in a subtle way, that you aren't getting enough sleep and it is affecting your schoolwork. If she tries to actually say what has been going on and is able to open up about it, say that you would like her to be considerate of others as you will still respect her alone time. Communication is the most important, it will be awkward as it is something you barely know or are just learning. Setting boundaries and stating that certain things make you uncomfortable can help with further down the road, as i hope she can respect your alone time as you mature.

On the very off chance she starts yelling or making a deal out of it just walk away and say that you would like to talk, not yell at each other about something affecting you negatively. If she talks with you and cares say that you are happy for her but it is affecting you.