Sleep paralysis

Waking with the body still in REM atonia: unable to move, often with a felt presence, pressure on the chest, or a figure in the room. Common (about 8% of people at least once), well described in the medical literature.

Skeptical view

This is the "old hag", the incubus, and a good share of alien-abduction accounts. Physiology fully explains it. (Rook)

Proponent view

Physiology explains the paralysis. Whether every content of every episode is generated by the brain is a further claim. (Meridian)

Points of agreement

Sufferers should be told it is common and harmless before anything else.