Interesting this is on the feed of recent posts. This just happened to me for the first time Sunday morning.
It was interesting.. I was wide awake conscious, knew where I was and felt fine. Something was touching my back though and that was what woke me up. I went to roll over onto my back but realized I couldn't move. Mine was caused by stress & sleep deprivation so I'm hoping it doesn't come back this tax season. But I found it really fascinating even as it was happening. I wasn't scared, I was intrigued.