Incubus (band) named themselves after this.

In medieval legend, an incubus (plural incubi; from Latin incubare, "to lie upon") is a demon in male form supposed to lie upon sleepers, especially on women in order to have sexual intercourse with them. A female version was called a succubus. There are several possible explanations for the incubus legends:

• They form part of the well-attested Medieval preoccupation with sin, especially sexual sins of women.
• Actual rapes of sleeping women were attributed to demons by rapists in order to escape punishment.
• The feeling of smothering while sleeping is known to physicians. The modern term for this common disorder is Sleep paralysis or sleep apnea.
• Because of the weight given to sexual sin in the Middle Ages, nocturnal arousal, orgasm or nocturnal emission were explained away by the legends of creatures causing an otherwise guilt-producing and self-conscious behavior. Thus people could say they were not to blame for it; it was obviously outside of their control: they were a victim.
• Young women/men being sexually assaulted in their sleep by a known attacker such as as friend or family member, although not common, has been reported and may explain some "nocturnal" attacks. The victims may find it easier to explain the attack as "supernatural" rather than confront the idea that the attack came from someone that is trusted in the family . See incest or situational molesters

During the witchhunts, alleged intercourse with demons or with Satan was one of the purported sins for which women were killed.

See also: Pan, Witchhunt, Succubus, Sleep paralysis, Diabolical pact, Francesco Maria Guazzo, Mara, Witch trial, Classification of the demons, Spina's classification of demons, Nature and appearance of the demons, Sexual relationships between demons and humans, Sexuality of the demons, List of specific demons and types of demons, List of sexology topics, Lust in demons, Incarnation of the demons, Demonology