So distressing. I was trying to find more information on this because it is an intriguing condition (I don't minimize the terror of the disorder as I say this). I did find a very thorough, intelligent, researched-based paper out of the University of Montreal. This may not add to your knowledge of the disorder, but perhaps you might find it interesting. I couldn't find a date for it, but it does cite relatively recent sources. Here's the link
Sleep Paralysis: phenomenology, neurophysiology and treatment