You said you were burned out and went to bed around 6:00. Did you drink enough water on the way in, and did you cook and eat supper before turning in? If not, those could be contributing factors.

More likely is the BA Air Core pad - just like everyone else said, it's no good in colder temperatures, and I had the BA Insulated Air Core pad let the cold through at about 35 degrees.

And, just to nail down all the loose boards, if you were using the insulated pad, did you have the maroon side on top? I believe the insulation is attached to that side, and hangs down to be effective - if you used it upside down, the insulation didn't "fluff" properly. (Anyhow that's what the local outfitter asked when I told him what happened to me.)