Not sure about memory foam. I do have a latex bed and it is very warm. There's some memory foam built in on top of it cause it's pretty firm. And yes it's pretty warm! I don't need a comforter in the winter - although our winters are fairly mild. I turn up the AC when I sleep and put on the ceiling fan cause I get uncomfortable.
But it sure is saving my back!
I wonder about those massage pillows that you sit on. I could even plug it in and get a little massage.
