We have all heard the stories of people waking up from a sound sleep only to realize that they are unable to move, the idea of demons(incubus and succubus) that sexually assaulted men and woman while they were sleeping was common through out history.
Today people still report being the victim of an incubus or succubus attack or possibly an alien abductee. The reason for this strange phenomena is a sleeping disorder known as sleep paralysis with hypnagongie and hypnopomic hallucinations or more commonly sleep paralysis. As many as 30% of the population experiences sleep paralysis.
Sleep paralysis is a natural condition , one that occurs when someone is about to drop off to sleep or just waking up realising that he or she is unable to move, speak, or cry out. This may last a few seconds or several minutes, rarely do they last longer. Feeling a malevolent or threatening or evil presence in the room is very often described. The paralysis is caused by the release of hormones during rem dream state that paralyses the body and keeps it from acting out the contents of the dream. Usually the hormones dissipate before the dream ends and the dreamer awakes In rare cases the hormone does not dissipate before the dreamer wakes up, leaving them unable to move. Sleep paralysis happens most frequently when the dreamer is lying flat on his or her back
The best way to end an experience of sleep paralysis to will yourself to move even if it's just wiggling your little finger.