Don't worry too much about it. There are all kinds of people at the school...it shouldn't be too bad. You might have the best luck trying to live in a substance-free dorm, or on an honors floor. They tend to be quieter, and the people are guaranteed to be more serious about school than partying. I think it could be good for you to be in a double room (but not a triple or a quad), because it will give you this day-to-day practice of living w/someone who isn't a family member. It can also make it a little easier for you to meet people. You may even be able to get with disability services to request someone who's in a similar situation as yourself (or finds a schedule important, etc.).
Freshman year I ended up w/a roommate who had a nervous breakdown, then moved out...then a cool girl who'd struggled w/drugs in the past but was clean. Sophomore year I lived w/a soccer player, and we got along great until she got engaged and transferred schools to be closer to fiance. Junior year (still in the dorms! the apts. in town were crappy) I was randomly assigned to a totally weird freshman who put giant framed photos of HERSELF all over the room. I was in an entomology class...pinned bugs in the freezer were just a BIT too much for her. Then, my favorite roommate, a cross-country running education major moved in w/me. She just had her first baby this month.
I never would've interacted with ANY of these people if I hadn't been forced to. I learned to stand up for myself, and I also learned that I can get along with anyone, if I work at it. It's good to learn those skills when it doesn't really matter, rather than trying to learn them on-the-job later one. Also, I perfected my "5 minutes of small talk" during that time. It's saved me too many times to count.
Also, it can be cool to live w/an athlete, someone w/a GF back home, or upper classman sometimes b/c they'll be gone a lot, and you'll have time to yourself. Good luck! Have fun...it's liable to be the best time of your life.