If they gave you steroids to take (I can't remember the name - isn't it good that you can eventually forget stuff like this) they do impact on your ability to wind down.
When I had my first surgery, I spent the whole day in the hospital room going for tests then returning but mostly just waiting. The room had a balcony but the doors were firmly locked as apparently the risk of a balcony outweighs the original design of fresh air. Anyway, I remember joking to my surgeon (joking being the way I was covering up my fear) that the doors were locked because otherwise we patients would abscond while no-one was looking. Well...it was kind of a joke.
Take care.