with the majority of my lucid dreams, I've woken up from them lying on my back. I hardly ever sleep on my back as a result of it not being as comfortable. If I try to fall asleep on my back, no matter how tired I am, it just seems to keep me awake. Perhaps this has something to do with bringing on lucidity for me. Who knows, but worth looking into.[/b]
Yeah, I think there's a few posts about sleeping positions. I remember reading that lying flat on your back seems to work better for WILDing. It's usually the position I'm in when I try WILD. It might have something to do with feeling "centered". Or maybe the fact that none of your body parts are overlapping each other, which, after a while might cause discomfort.

I'm usually most comfortable on my side, but after a while my shoulder either starts to hurt or goes numb.