I've always understood that layers = warmth but I just had someone in one of my classes say that sleeping bags work better when your naked. I just wanted to see if there was any fact behind this statement. I know adding layers on top of what I'm already wearing makes me warmer but I've never slept naked or close to it in colder temps to really see if it does make a difference. Personally I think he doesn't know what he's talking about but figured I would ask around before I assume him wrong..