Open another browser tab and google “The Nightmare Henry Fuseli“.
This 18th century painting is disturbing: it depicts a woman swooning in deep sleep, a chimp-like demon crouched on her torso.
The creature is an incubus, a type of demon that appears in folklore around the world (it’s also commonly known as a succubus) and is notorious for visiting its victims at night, rendering them unable to move and filling their minds with dread.
What causes sleep paralysis?
The modern scientific explanation for the incubus is sleep paralysis, a condition where you’re unable to move or speak when you fall asleep or wake up, often accompanied by dream-like hallucinations or strong emotions.
Your body naturally “paralyses” itself during rapid-eye movement (REM) sleep to stop you acting out what you’re dreaming, and when this system malfunctions it’s thought to cause sleep paralysis.
“You get the paralysis of REM sleep that is a normal phenomenon, but occurring before the brain actually goes off to sleep, so you’re aware of it,” Professor Ron Grunstein, a sleep disorder specialist from the Woolcock Institute of Medical Research