...Lucid daydreaming button, anyone? Maybe not lucid if it's the exact same as normal sleep, but I'm sure that if such a thing more exist, you'd be able to adjust exactly how it affects your brain.
Tell that to sleepwalkers!
- Sleep paralysis doesn't properly activate, and someone accidentally transfers the motion of walking into real life. proprioception may pass through to the dream, they might perceive a dream environment that allows them to navigate the real one. (i.e. righting themself from bed, staying upright while walking)
- They aren't fully asleep, but they aren't awake/aware either. I've had my fair share of people telling me that I said or did things after waking up and before immediately going back to sleep, and those are things I don't remember doing at all, probably because they weren't properly recorded in memory because my brain was not fully awake. (Some of these cases could have been DID though.)