Sleep paralysis at home and abroad

I don't think I have mentioned this before - my teenage daughter has, over the last year or so, began to experience episodes of sleep paralysis.   All the classic stuff:  waking up and unable to move, and a dark entity moving towards her bed.  Tries to call out but can't.  She recognises that it most likely would happen when very tired before bed, and sleeping on her back instead of her side.  She said that in successive events, the dark entity was getting closer and closer to her bed. 

Fortunately, I think I had told her about this before she had her first episode.  (Seems to me it's probably a good idea to warn all children that this is a not so rare occurrence that they might experience, and they should not read too much into it.)   The point is, my daughter finds the experiences disturbing, but also understood what was going on from the first time.  (I think she realises what it is during the event, even though she can't stop it.)

Anyway, I'm talking about this now for two reasons:  there is an article at NPR summarising the phenomena, and a couple of weeks ago I was reading a Reddit thread about it, where someone commented that they thought it likely that this was the likely explanation for widespread belief in demons, witches and/or malevolent spirits across all old societies.

Oddly enough, that latter thought had not really occurred to me before - it may be a key element in the widespread belief in a supernatural realm generally.  

Here is some interesting information along those lines from the NPR article:

About 75% of the time, those experiencing sleep paralysis will hallucinate. "Most of the time, we'll hear that it's something frightening," Kushida says. "But there have been instances where a person will report that one of their loved ones was there."

In fact, the hallucinations typical of sleep paralysis are frequently influenced by a person's culture and described in terms of "paranormal activity." There are descriptions from Newfoundland of an "Old Hag," or witch sitting on the person's body. In Japanese folklore, the same phenomenon is called kanashibari, which means "bound in metal." Some researchers think sleep paralysis is to blame for reports of alien abductions.

This prevalence across cultures makes sense in light of Pennsylvania researchers' systematic review of scientific studies across a 50-year period. The review estimates that 8% of the general population has one episode of sleep paralysis in the course of their lifetime. The study found that this number is variable within populations. For example, more than 30% of psychiatric patients had an episode of sleep paralysis, and the disorder is most common in adolescents.

This is not to say that I don't believe in supernatural events at all - but it does seem a very plausible argument that people believe in devils and demons in particular because of this natural, medical phenomena.