Is there such a piece of furniture as a wide or double day bed, or a bed that has a tall cushioned side to it? I have a tremendous amount of trouble sleeping in a regular bed. I sleep so much better on a sofa, where I can put my back to the back of the sofa, if you get what I mean. Pushing the bed to the wall and sleeping against the wall doesn't really help. Any suggestions on a piece of furniture that might be suitable would be very appreciated!

What about using body pillows? These are 5' long pillows. You can stack them against the wall to work as cushions like a sofa.