Alright, so granted, I'm not that far into the game. I've got Traverse Town and Cite des Cloches beat and Sora's half of the Grid. But I still can't understand what exactly is a sleeping world. Traverse Town made me think that a world that's stuck in dreamland is split into two versions that have certain overlapping segments, but it seems like Grid and Cite have two versions that aren't overlapping much. Sora and Riku are going through two different versions of each world, but the inhabitants -save for Traverse Town- don't seem to realize that the world isn't awake. It's not stuck in some form of stasis as people are going on with their lives and things change and they learn new things. What makes it sleeping? Why are there exactly two versions? Why exactly can't Heartless and Nobodies find their way there if Nobodies come from nothingness and the Heartless taking those worlds over is why the worlds are asleep? How exactly are these "sleeping" worlds different from "waking" worlds?