Others see bright lights and swear they were abducted by aliens. Neurology offers them a better idea of how common it is and what the risk factors might be. According to a new study, roughly 6 percent of all people have had at least one episode of sleep paralysis, while slightly less than 1 percent have at least one episode a week. Sleep expert Dr. Maurice Ohayon and colleagues came up with those figures by asking 8,100 people in Germany and Italy about their sleep habits. Ohayon, a researcher the University of Montreal, says he would expect the prevalence rate to be about the same in other countries, too.
Few people report the problem to a doctor.
While some hallucinations may be powerful enough to trigger anxiety or depression, the study should reassure people who worry that their sleep paralysis indicates a brain tumor. Ohayon said that in most cases, sleep paralysis is not linked to neurological disease. While 6 percent of the population may sound small, Dr. Michael Thorpy of Montefiore Medical Center in New York City says that's fairly sizable for a sleep disorder. Sleep apnea, when breathing stops during sleep, occurs in only 4 percent of adult males. Narcolepsy registers a scant .05 percent.