I sleep in cotton broadcloth pajamas, and reading this thread gives me some idea of why I have such a hard time finding new ones: hardly anyone is wearing pajamas anymore, apparently! Sleeping in the underpants that one has been wearing all day seems to me a bit unhygienic; at any rate, I like to let my private parts get some air at night. On the other hand, I don't feel comfortable sleeping with nothing on, especially not during the cooler seasons. So pajamas it is.