I swap regularly between right and left, but other that that, I can only ever sleep on my side, more or less in the recovery position.
Even after chest surgery when I should have been sleeping on my back to keep my weight off the incisions, I would end up rolling over before I passed out, because I just couldn't sleep otherwise.
While I don't know for sure, I fully suspect my back has something to do with it; the curve in my lower back is exaggerated, so putting stress on my spine (even just from standing still) becomes painful rather quickly.
I swap regularly between right and left, but other that that, I can only ever sleep on my side, more or less in the recovery position.
Even after chest surgery when I should have been sleeping on my back to keep my weight off the incisions, I would end up rolling over before I passed out, because I just couldn't sleep otherwise.
While I don't know for sure, I fully suspect my back has something to do with it; the curve in my lower back is exaggerated, so putting stress on my spine (even just from standing still) becomes painful rather quickly.