Sounds like lucid dreaming?
You're lucky to get these often. People spend months training themselves so that they know when they are dreaming.
I used to get these when I was younger - Be dreaming and become aware that I was dreaming, and then go around robbing banks and doing all sorts of crazy stuff, but once it started to get exciting, id always wake up
I later learnt a cool way to stay in you 'lucid' state but have only managed to get the chance to use it a few times because I hardly ever lucid dream any more...
My suspicion,is that lucid dreaming/semi lucid dreaming is where the sleep paralysis lies. I've had these for as long as i can remember, not necessarily 100% correlation by any means, but it appears the area of the brain controlling it is, or must be similiar.
I cant count the number of times an alarm clock has gone off, ive got up, been active for ages, eaten breakfast etc, only to eventually realise im still asleep in bed and havent moved at all.
Despite not "legitimately " meeting the definition of lucid dreaming, incorporating external stimuli into these dreams-and often, being aware of it- means something odd is happening, right?
I used to find, coffee after 11am, and napping in a light-ish room produced those results, from actual lucid dreams, to fully aware dreams with complete paralysis/lucid terrors/etc.
Sucks big time, actually.
Also had the "crushing demon", scared the heck outta me-thought it was a ghost/poltergeist, and treated it as such-despite my conscious mind saying"thats ridiculous, must be some physiological explanation. "
Although, it was no worse than the usual, i think they are normally called "night terrors", which differ from a nightmare......largely in the fact the mind has some awareness, partial control i guess, but not enough to just break the sleep paralysis/terror stream of weird crap flashing across the minds eye.
Yeah, sucks big time.
Anyone get the "rushing" terror? Only way i can describe it-deafening , rising noise, like a jet engine, it can appear to emanate from different angles etc ive found-but produces just mind numbing terror, yet, for no apparent reason. Invariably during partial /semi lucid sleep paralysis, particularly with light in the room.