the entity

Summary:
Throughout time and across cultures the Entity, a dark, mysterious visitor, has invaded people's dreams. It features in all cultures across the world across history, people claim to be awoken with a sense of being attacked and suffocated by some form of humanoid spirit.

This disturbing documentary examines this archetypal nightmare - where does it come from and what can science do to explain it? Are scientific explanations that they are the result of sleep paralysis, where the person is awake but still dreaming, satisfactory?