Staying in a hotel where you can't open the windows. How do I cope?

I'm probably going to stay at a hotel where I can't open the windows. I've been to hotels like this before and I always have trouble sleeping. I feel I'm out of breath. It doesn't help that I have asthma so no matter what I try and do to relax it doesn't work.

I don't think I can "get out" of staying in a hotel. Have you had to do something like this before? What did you do? How did you end up having a restful sleep?