We all know about vampires and werewolves, or at least we think we do. The legends and myths that inspired these monsters are sometimes surprisingly different, but no less chilling. In this series of posts, Monster Monday, we’ll investigate the monsters that have informed our modern notions, as well as some lesser known monsters. Today, we talk about the Nightmare.

A nightmare is an evil spirit or demon that visits a sleeping person in the night and sits on his or her chest, trying to suffocate or strangle the person. They are also said to ride horses to exhaustion.

In some parts of Europe a nightmare is said to resemble a beautiful woman who tortures men in their sleep and can drag the life out of them. In other legends, a nightmare can take the form of an animal, often an insect like a bee or a wasp or a moth. In still other versions, a nightmare is the soul of a living person that leaves the person’s body at night.

In some stories a nightmare is said to enter the house through the keyhole. There are various means of stopping a nightmare, including putting a broom upside-down behind the door, putting a belt across the bed, or reciting a special prayer.

The legend of the nightmare, was probably inspired by the phenomenon of sleep paralysis, in which a person upon falling asleep or waking up experiences an inability to move, usually because of some disruption of REM sleep.