Why is she such an idiot?

Well seeing how it is not just her room I would continue doing what you want to do lol If she has her headphones on put your Jack Johnson on and see if she notices... if she does then why not just put headphones on yourself? As for the light situation, if it is a reasonable time during the day you should tell her if she wants to be in the dark put her covers over her head, but some of us want to be productive and see OUTSIDE... roommates can be dumb... hopefully you can get a new one next year and pick your roommate? Or get your own room : /