I've been sleeping ok on a firm mattress for 2 years. Then a few weeks ago started to wake up with severe back pain.
I experimented with different sleeping surface, pillows between knees, under the knees, etc. Then I saw pictures of adjustable beds, so I prop up my upper body with pillows, cushions, and it works! I think I will bite the bullet and buy a real adjustable bed.
Has anyone else have this experience? Is there an explanation why this helps? It is counter intuitive because propping up the upper body puts some weight on the spine whereas sleeping on a flat bed does not.