Definitely talk to the RA, and try to get another roommate if at all possible. The possibility of getting into something just as bad or worse is always possible though. So keep that in mind and consider both the pluses and minuses of your situation.
i think the first thing that you both should do is get the supplies that you need to survive sharing a room. It is not an easy situation when you are a kid and related to your roommate and there is no way that it will not be awkward with someone you don't know or don't like. get a sleeping mask and some soft earplugs to get through the night, you both should have them, as well as headphones.
Maybe you could come to an understanding about what times it is OK to have the light on and such. Both could agree that if one of you needs to do something that will be disturbing then do it outside of your room. But if all you are doing is getting on the computer quietly then a face mask will be such a great help.