I sleep wearing a vest top (t-shirt if it's too cold) and some bottoms. On very hot nights, I might go topless. If I get too hot, I kick the duvet off and just sleep cuddling it lol.

I find sleeping naked to be uncomfortable, the few times that I have. Even going topless is a little uncomfortable. I dunno... I don't feel protected without any clothes on.

'Special circumstances' may be different. *shrug*