1TRAK, I used a standard Thermarest for years, but the last few times out I realized I had just gotten too old or something. I couldn't stay warm even when it wasn't that cold out, and my elbows would always end up off the mattress and on the ground, and I'd wake up because it was like I was resting my elbows on blocks of ice.
So last year I shopped for a new camping mattress and bought this
Exped Downmat 9. It's an air mattress that inflates to be several inches thick, but it has a down layer that keeps you from freezing your butt off from the could air underneath. It's wider than my Thermarest was, so my elbows don't touch the ground, and it's longer, warmer, and protects better from the lumps in the ground. It has a stuff sack that doubles as a pump. It is easier to inflate and easier to deflate, and packs about the same size as the Thermarest did. It is however pretty expensive. I am still glad I got it. Since I got it I have been sleeping as well in the tent as I do in my bed at home.