Currently have a Nemo Astro insulated pad. Very warm and comfortable, though I seem to wake up with a sore lower back every time I use it. No pre-existing back problems, my back is perfectly fine otherwise. I am mostly a stomach and occasional side sleeper. I have tried all different levels of inflation to try to find a "sweet spot" as far as the back issues go. No luck. I am assuming it is from the pad sinking a bit in the middle as I lay on it creating an arch in my back. Has anyone else had this problem? Is it likely I will run into the same issue with every inflatable I try? Do you think I would have better luck with a foam pad (those look so uncomfortable though, ugh!)? Any recommendations for a new sleeping pad to try that may help me? Thanks.