YoDuh - Why are you advising people to sleep UNDER a sleeping bag and presumably IN their clothes? You should sleep IN your sleeping bag with your underwear and if it's really cold with socks and a hat/beanie. You can then use your clothes (jackets, pants, shirts, etc) as EXTRA warmth and put them ON your sleeping bag. If you sleep IN your clothes you are relying on them to retain your body heat and keep you warm that's your sleeping bag's job. Getting off the ground is important but not at the expense of having no way to retain body heat other than a sleeping bag on top and your clothes around you.
BTW: "velcro" on the sides of a bag isn't exactly a proven insulator <img src="/images/graemlins/wink.gif" alt="" /> (read; heat loss, or coming undone in middle of night with slight movement)

Seeker890- Sleeping on an air mattress and trying to stay warm don't go in the same sentence unless it's a therma-rest or the like however I don't think you would have said 'inflated it' if that's what you were refering too. I remember once I slept on an air mattress in the snow... biggest mistake ever! Therma-rest 4reason for me and always toasty now!

-Todd