I am using Signature Design recliner due to ankylosing Spondylitis, a form of severe Arthritis -cartilage of the spine (mainly) turned to calcified bone.
I read the complete details here then At first I was sleeping on the chair half-reclined, but as time goes by, I reclined it all the way back, which is almost 170 degrees, almost flat. The full-recline option is great because it trains my chest making it ready to finally return to the normal flatbed.