What happens to dreamselves when they wake up? do they poof back to bed or just pass out where they're standing

If there is a bed to poof back on to, yeah they return to the Moon. John’s Dream Self seemed to disappear when Prospit was destroyed and he was in the Battlefield, but it’s also possible his Dream Self got teleported to the Quest Bed tower of the Battlefield then rather than during his ascension.

Of course, if the Dream Self is the only version left alive, they act just like normal bodies.