If you haven't seen the documentary ''The Nightmare'' yet you really should. Its about sleep paralysis... and features an extremely unbiased view of the subject which touches on a variety of different reasons/explanations such as genetic factors, social factors, etc all the way up to spirituality and extra dimensional entities. As somebody who experiences sleep paralysis about once a month and has been through times, especially at the Tower, when it was every night, I can say that the way in which it is portrayed and the confusing/terrifying experiences that go along with it are extremely accurate.
To some extent I think the most plausible explanation for this is unrecognized shamanism and these unfortunates should have been exposed to systems which helped them train the mind and explore the spiritual realms. They look like Shaman-flesh too. Some of the pre-paralysis ''hallucinations'' shown in the documentary very closely simulate what the early parts of the astral plane look like - coloured blobs, geometric tesselations, scintillating fields etc - and often the people are pulled back from the astral and trapped in their physical body. Some describe OBEs and being able to see their astral thread.
I understand now that there is a pay-off to my predilection for sleep paralysis and this is the ability to explore the astral plane alongside lucid dreaming. I know,from experience, that hypnapompic hallucinations are way more pleasurable than hypnagogic - like many other victims/patients in the documentary I have developed coping strategies that reduce the terror of the latter. The shadow man, made of static, has shown himself to be an angel numerous times* for ''every angel is terrifying'' - their apperance much like that portrayed by the character of Indrid Cold in the Mothman Prophecies along with their ability to tell me things I could not possibly know.
In the Hekhalot literature the planes of heaven, i.e. higher planes of consciousness/other dimensions** are protected by accusing angels and in order to pass them you must use the correct words - I have spoken about this at various times in the Hermetic Lessons. In my understanding the individuals shown in the documentary get trapped bewteen Malkuth and Yesod or Assiah and Yetzirah, the sleep paralysis ''zone'' being on the path of Tav which the erroneous Kircher Tree attributes to Saturn and which I attribute to the Moon. It is very easy to state that conquering your fear is the way in which to bypass this sleep paralysis ''holding cell'' but people who do not experience it regularly can't understand just how absolutely terrifying it is. People also need to be aware that these terrifying guardians are there for a good reason either 1) you are not responsible enough to mess around on the higher planes or 2) you are a legitimate threat to the higher planes because you carry the curse of violence. The sleep paralysis cell is actually one step more free than the cell which you nominally occupy in the ''physical world'' - perversely. If we can liken it to Plato's analogy of the cave, sleep paralysis is like ''knowing'' that you are chained to the ground staring forwards at shadows all the time, which we forget on a day to day basis when confronted by the illusions of depth, colour, etc created by our mind.
In the past Kabbalists argued about whether the ultimate nature of Kether was love or fear. As you can read here many of the alternate names for Kether speak of absolute destruction, annihilation and darkness. The Sefer Yetzirah warns us to run and return, lest we are obliterated by the divine kiss. The Kabbalist explores the tension between love and fear and recognizes the existence of both in the Godhead - the light that draws the moth in is beautiful but it burns.
Although sleep paralysis is an extremely harsh experience to endure it has propelled me rapidly along a path to greater understanding. I have had to come to terms with direct experience of these entities along with extreme vulnerability in their presence, my spiritual path has not been spent chasing fairies in the woods or looking for goddesses in the waterfalls. The experience is not a hazy, fleeting one, as you can see in the eyes of the people who have experienced it. It lasts a long time and is never forgotten. Ultimately though it is a gift and probably a genetic one - like I spoke of before about epilepsy and diabetes obfuscating great gifts so does sleep paralysis but in a society that does not explore dreams or spirituality, or discuss the nature of imagination and creativity these gifts can often go unrecognized as the person focues on the disadvantages of their condition and has no understanding of the benefits gained or the losses they will incur if ''treatment'' is successful.
*Mainly Uriel or Raziel in my experience.
**I think these are probably the same thing, not that this is a ''psychological model'' just that everything in the universe is fundamentally mind not matter.