"...persons suffering an attack suffer an incapibility of motion, a torpid sensation in their sleep, a sense of suffocation and oppresion, as if from one pressing them down, with inability to cry out, or they utter inarticulate sounds. Some imagine often that they even hear the person who is going to press them down, that he offers lustful violence to them but flies when they attempt to grasp him with their fingers"

"I remember waking up flat on my back. Paralyzed ... Terrified beyond anything I'd ever experienced before ... Sensation of pressure on my chest. The terror! The terror was both from being paralyzed and I knew there was something else in the room."

The word Nightmare comes from an old Saxon word, mara, meaning 'crusher'. The true nightmare experience is like the ones quoted above: it can include a sense of crushing weight, difficulty breathing, absolute terror and an inability to move. Importantly, sufferers correctly perceive their surroundings (in contrast to a dream state where their surroundings could be distorted or false).

Slightly less common features of the attacks include a feeling of threat or evil nature from a supernatural being which can sometimes be seen. Sounds are occasionally heard and victims sometimes feel that they are in danger of dying. Sexual feelings may sometimes be evoked although this erotic aspect does not arise from attraction: the supernatural attackers more often more resemble repulsive demons than alluring lovers.

Since the seventeenth century the term 'nightmare' has been denatured by being used in a less specific sense - the sense of simply a 'bad dream'. But the true nightmare experience, called by a variety of names, has appeared constantly throughout history and may even be present today in the form of UFO abductions. Around 15 percent of people have suffered from a recognizable nightmare attack and that 23 percent of people have woken up in the middle of the night and found themselves unable to move or cry out.

The German bringer of night terrors was the known as the Alp, a word related to 'elf'. It was described as "Some kind of being, most often a shaggy animal, or else a hideous human form presses on the sleeper's breast, or pinions his throat and tries to strangle him". In the Middle Ages, the Alp often appeared in the form a cat, pig or other animal. There was even an episode at a Cologne Nunnery where a 'lecherous dog' was assumed to be a lewd demon. The Alp has widely been regarded as simply the German counterpart of the incubus or nightmare, with no appreciable difference in habit. Saxon English/German tradition has the Hag or Hagge, a descendant of which was studied in Newfoundland by David Hufford in his seminal work The Terror That Comes in the Night. The Hag crushed a person with her weight on his chest and caused her victim 'nightmares'.

Similar to the Hag/Hagge, the Mara was a fiend who could adopt the appearance of either a beautiful woman or a hideous hag. Belief in the Mara was widespread through Europe and Scandinavia: the term (and its alternate "Mera") was Old English, derived from the word for "demon". The southern Slavs believed that the Mara sucked blood as well as bringing nightmares. Once she had tasted a man's blood, she was impossible to dislodge and would not leave him until death. Surprisingly for so ephemeral a creature, she was prone to injury from sharp objects. If sprinkling sand in the air and uttering incantations failed to reveal and repel her, a victim was recommended to lay on his back clasping a knife with the point upward between the hours of 11 pm and 2 am, when she visited. By this, he would cause her an injury which would make her leave.

The Hebrew Zohar attributed nightmares to female demons lying with men to produce more demons and Hellenistic illustrations have been known to depict naked lamiae straddling across men asleep on their backs. Other examples include the Aswang of the Phillipines, the Schratteli of Switzerland, the Kikimara of Russia, the Civateteo of Mexico, the Autu of Borneo and the Mrart of Australia.

And the evil agent of nightmare has at times been identified as a witch. Cotton Mather, wrote that Bridget Bishop (of the infamous 'Salem Witch Trials) had allegedly "ridden a man", one Richard Coman. In France and Louisiana, the witch fiend is known as Cauchmar.

Since at least classical times physicians have attempted to treat this distressing experience. For many centuries, the culprit was thought to be gastric disturbance - hence the idea that eating cheese before bed will give you nightmares. This theme developed to include possible circulatory distress while sleeping supine. With the advent of psychoanalysis, it was felt to be an expression of unresolved psychological conflicts.

But the subject has come into clearer relief with modern science and study of the biology of sleep, explained in Trying to Avoid Nightmare.

The full history of Nightmare including and its interpretations in modern times are discussed fully in the book of Unnatural Predators. To find about about this and other Unnatural Predators events, site updates and merchandise, join our mailing list.