Sleep paralysis

From Veritas

Sleep paralysis, or paralizing spazima, is the clinical condition by which the physical body become immobile during sleep. This immobile state is connected to the release of the chemicals acetylcoline and dopamine. Symptoms of those who become conscious may include trouble breathing, sitting up, or experience panic.

In history, the word nightmare had been connected to this state. It was thought that demons (inccubi, or succubi) would visit sleepers and take sexual advantage of them.

In the psychic field, sleep paralysis is said to be a symptom of etheric projection. People who have such experiences report feeling paralized, before exiting their bodies.

Recources

Stanford University