I used to know a few people who had this, but the most amazing fact was that they knew what sleep paralyses is, and still they were utterly terrified.
They knew it is harmless and it was of no help.
I could never jump out of a bed instantaneously on an alarm, there is always like a few seconds of a complete numbness, but I never experience any panic episodes over it. Maybe these people experience a prolong waking cycle due to the nature of their brain functions. I don't think that the panic attack is part of it, that is in my belief completely subjective.
Anyway, great and interesting article with lots of info.