After various discussions with girl friends, I've come to the conclusion that what people wear to bed is almost always a strongly chosen choice, and often, the other options are not even options. People like to wear to bed what they like to wear to bed. Doing something different is uncomfortable and not liked.
For me, I used to be a big fan of boy shorts and a tank top, just a few years ago. Since then, I've been slowly losing my clothes, down to undies, and now my preference is to sleep naked (gasp!). Part of me just feels the most comfortable like this, but another part of me feels, 'Why dirty more clothes than I have to?'. That said, I love lingerie, but typically, not when I'm alone.
What about you? Are you strongly set in what you wear to bed?