I have a hammock but haven't figured out how to seriously sleep in it outside yet, so I'm still a ground sleeper.
I used to use just an air mattress under my sleeping bag, but it always got cold. Now, thanks to wisdom shared by those more experienced than me, in cold and/or damp weather, I use a multi-layered system: I put a thermal hunter's mylar blanket on the ground, (mine is a Coghlan's brand but I'd like to upgrade to the SOL version - https://www.rei.com/product/820923/sol-sport-utility-blanket) and then two air mattresses - a closed cell foam pad on the bottom (Thermarest Ridge Rest or a simple blue foam pad) with my inflating Thermarest on top. In really cold weather, I'll often wrap my sleeping bag in a wool blanket, so I have some under and over me.
My sleeping pads are about to be stolen by my daughter, who is fast outgrowing her toddler gear, so I'm in the market for a new insulated mat for myself. There are lots of options for us old arthritic folks so research is underway!
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