I have realised something about the saga of my bed constantly hurting my back: The bed not being level (due to my upstairs floor being uneven) isn’t just uncomfortable in and of itself, but probably results some of of my weight being shifted from a compressive force that the mattress springs are meant to take into a sheer force that they are useless for, rendering my mattress less firm, less comfortable and less effective.

I had already been using boards to level the bed but the other night I made a more fine adjustment putting a few layers of cardboard under some of the legs and even that minor height adjustment has made a huge difference in comfort.