Hi, Phat: just to clarify, I wasn't "cold" at 25, as in "I'm shivering, I'll get up, put more clothes on, and light a fire." 25 was the temperature at which I could start to feel cold air seeping up through the pad (yes, I had it right side up so the insulation hung down.) It was enough to make me think, "Huh, that's interesting" at which point I went back to sleep for a couple more hours, until daybreak. I suspect that it happened at the coldest point in the night; a pad underneath, or putting on more than my long johns, would have solved it. I was also using a 30-degree bag (WM Megalite), so a warmer bag might have made it unnoticeable, too. (It was definitely a case of cold seeping up from underneath; my top and sides were plenty warm, so it wasn't the bag.) As I re-read the post, it does appear to be a bit IAC-bashing; that wasn't the intent. It was just meant to be an example of the parameters of the answers I was seeking.