I also note that the girls are used to having A/C in their bedrooms.
Also, all you naked sleepers... what do you do if you need to go to the bathroom in the middle of the night, and you live with people you might run into? Throw on a bathrobe?
Reasons not to sleep naked:
You live with people you don't want to see you naked (or who don't want to see you naked)
Ablative sweat/skin/groin-stuff absorbing layer between you and the bedsheets, so they need to be changed less often.
You need them for warmth even with blankets and such.