To me, this sounds like a produce of sleep paralysis. I've only ever experienced it full-blown once (I usually pull off WILDs without any form of SP), and during that incident I experienced something very similar - the difference between me and you being I didn't actually enjoy it, but I knew what it was and what was about to happen, so I intensified it. If you ever get this again, let it take hold. You may find yourself suddenly in a dream.