About once a week, Jean-Christophe Terrillon wakes up and senses the presence of a threatening, evil being beside his bed. Terror ripples through him, and he tries to move or call out.
But he is paralyzed, unable to raise an arm or make a sound. His ears ring, a weight presses down on his chest, and he has to struggle for breath.
''I feel an intense pressure in my head as if it's going to explode,'' said Mr. Terrillon, a Canadian physicist doing research in Japan. Sometimes he finds himself transported upward and looking down on his body or else sent hurtling through a long tunnel, and these episodes are terrifying even for a scientist like him who does not believe that evil spirits go around haunting people.
What is Sleep Paralysis?
Called sleep paralysis, this disorder -- the result of the disconnect between brain and body as a person is on the fringe of sleep -- is turning out to be increasingly common, affecting nearly half of all people at least once. Moreover, a growing number of scholars believe that sleep paralysis may help explain many ancient reports of attacks by witches and modern claims of abduction by space aliens.
''I think it can explain claims of witchcraft and alien abduction,'' said Kazuhiko Fukuda, a psychologist at Fukushima University in Japan and a leading expert on sleep paralysis. Research in Japan has had a headstart because sleep paralysis is well-known to most Japanese, who call it kanashibari, while it is little-known and less studied in the West.
''We have a framework for it, but in North America, there's no concept for people to understand what has happened to them,'' Professor Fukuda said. ''So if Americans have the experience and if they have heard of alien abductions, then they may think, 'Aha, its alien abduction!' ''
The Experience of Alien Abduction Explained in Sleep Paralysis
Sleep paralysis was once thought to be very rare. But recent studies in Canada, Japan, China, and the United States have suggested that it may strike at least 40 percent or 50 percent of all people at least once, and a study in Newfoundland, Canada, found that more than 60 percent had experienced it.
There, as in Japan, people have a name for the condition and some scholars believe that people are therefore more likely to identify it when it happens to them. In Newfoundland, it is called ''old hag'' because it is associated with visions of an old witch sitting on the chest of a paralyzed sleeper, sometimes throttling the neck with her hands.
Sleep paralysis seems to have been described since ancient times and an episode appears in ''Moby Dick'' and perhaps also in the 18th century Henry Fuseli painting, ''The Nightmare,'' which shows a goblin sitting on the stomach of a sleeping woman. What is striking is that although the symptoms of sleep paralysis are generally very similar, the images in the hallucinations and the interpretation of them seem to vary.
Europeans seem to have interpreted ancient sleep paralysis as assaults or abductions by witches taking them off for a forcible ride on a broomstick. Chinese called it ''gui ya,'' or ghost pressure, and believed that a ghost sat on and assaulted sleepers.
In the West Indies, sleep paralysis was called ''kokma'' and meant a ghost baby who jumped on the sleeper's chest and attacked the throat. In old Japan, it sometimes seems to have been interpreted as a giant devil whose foot came down on the sleeper's chest.
''People will draw on the most plausible account in their repertoire to explain their experience,'' said Al Cheyne, an associate professor of psychology at the University of Waterloo in Canada. ''Trolls or witches no longer constitute plausible interpretations of these hallucinations. The notion of aliens from outer space is more contemporary and somewhat more plausible to the modern mind. So a flight on a broomstick is replaced by teleportation to a waiting spaceship.''
The Scientific Findings
Dr. Cheyne said that in a survey he had worked on involving more than 2,000 people identified as experiencing sleep paralysis, hundreds described experiences similar to alien abduction.
''A sensed presence, vague gibberish has spoken in one's ear, shadowy creatures moving about the room, strange immobility, crushing pressure and painful sensations in various parts of the body -- these are compatible not just with an assault by a primitive demon but also with probing by alien experimenters,'' Dr. Cheyne said. ''And the sensations of floating and flying account for the reports of levitation and transport to alien vessels.''
In recent years there has been a huge increase in the number of people who insist that they have been kidnapped by alien creatures from outer space, perhaps subjected to medical experiments and then released again. These claims have been a bit of a scientific puzzle because they strike most people as utterly wacky and yet they are relatively widespread. One well-publicized (and widely criticized) Roper Poll published in 1992 suggested that nearly four million Americans reported experiences akin to alien abduction.
Surprisingly, one study found that these people were no more fantasy-prone than the general population and had slightly higher intelligence. Many shun publicity and show signs of feeling traumatized and humiliated.
Several scholars have found that people are more likely to report alien abductions when they have been exposed to movies or books about the idea. Simon Sherwood, a researcher on sleep paralysis in England, said that in one case study he gathered, a regular sufferer of sleep paralysis watched an alien film and then had a hallucination of ''little blue aliens'' inserting a metal probe into his forehead.
The growing professional literature on sleep paralysis has often mentioned the parallels with reports of alien abductions. Still, many scholars are reluctant to research the connection for fear of tainting their reputations. Others say that a connection is plausible but unproven.
Tomoka Takeuchi, a Japanese expert on sleep paralysis who is conducting research at Brock University in Ontario, Canada, said that the connection might eventually be demonstrated scientifically but added: ''I hesitate to speculate too much.''
What Should You Know?
Those who believe in alien abductions deny that sleep paralysis could be behind it all. John E. Mack, a Harvard University Medical School professor who is the most prominent defender of the possibility of abductions, argues that sleep paralysis simply does not fit the evidence. He notes that at least a few abduction reports come from remote places where people are not exposed to movies or tales of U.F.O.'s and that many happen in daylight and involve people who seem to have been awake and alert.
Other defenders of abduction theories say aliens may be clever enough to use sleep paralysis in their kidnappings.
Sleep paralysis researchers say that as many as 60 percent of intense abduction experiences were linked to sleep and some of the reported symptoms -- noises, smells, paralysis, levitation, terror, images of frightening intruders -- are very similar to those of sleep paralysis.
Still, sleep paralysis cannot be a full explanation because some reports of alien abduction do not involve sleep. Leonard S. Newman, a psychologist at the University of Illinois at Chicago who has studied alien abductions argues that they are false memories -- in some cases triggered by sleep paralysis but at other times by daydreams or fantasies.
When she's not at her desk absorbing all the latest news and producing fresh content for her audience Carmina loves to spend time at coffe shops and dancing at local music festivals.