I wanted to post this comment that I read today about sleep paralysis. I found it very interesting and I tried to answer the question asked:
nice post - I never thought about SP in regards to the terrible biochemical combination of intense fear and muscle paralysis. it's a rough place for consciousness! I'm reading Hufford's classic right now and the accounts are fascinating. do you have any ideas about the phenomenon of the "stranger" (that sometimes accompanied the experience of SP) in terms of brain activity?
Sleep paralysis has been a long time been something that I have researched since I used to have it affect my life. The stranger you asked about I believe (if were thinking of the same thing) has been referenced by some people in the lucid dreaming community as the dweller. It seems to be the occurrence of a type of thing that exists in the dream that sometimes tries to scare the dreamer. At time this “dweller” has even been known to have long conversations with people of why it tries to scare people once the dreamer shows their inability to be scared by the object. I remember one account where someone ones reported that after having the conversation with the dweller, another dweller entered the room and explained to the other that it was time to go. Interesting enough I see the same references during psychedelic uses in the way they describe some of the “guides” that are experienced during some drug trips.
In trying to understand the brain chemistry that is causing this dweller effect, the easiest explanation that was explained in many of the books I have read about the processes of sleep, is that during the transitional phases between NREM and REM sleep the subconscious dominate. If by some chance there is a hiccup in this process (which is normally the case) the subconscious could become aware of the conscious mind and it causes an interaction. The amygdala being over active at this time and I believe a good explanation of why fear is the most referenced the interaction between the two. Psychedelic drugs could also cause a type of lucid state during the trip experience and cause the same type of interaction between the subconscious and conscious just on a larger scale. The relationship presented by Dr. Strassman and his work on DMT shows that the dream state and alteration of consciousness during sleep could very well be more psychedelic then we currently believe, and would explain more why the dweller effect happened in both cases.
I would be glad to hear more about what you have been reading, feel free to post your comments and ill try to get post more.