Background: Previous epidemiologic data on sleep paralysis (SP) came from small specific samples. The true prevalence and associated factors of SP in the general population remain unknown.
Method: A representative sample of the noninstitutionalized general population of Germany and Italy age > or =15 years (n = 8,085) was surveyed by telephone using the Sleep-EVAL questionnaire and the Sleep Questionnaire of Alertness and Wakefulness.
Results: Overall, 6.2% (5.7 to 6.7%) of the sample (n = 494) had experienced at least one SP episode in their lifetime. At the time of the interview, severe SP (at least one episode per week) occurred in 0.8% of the sample, moderate SP (at least one episode per month) in 1.4%, and mild SP (less than one episode per month) in 4.0%. Significant predictive variables of SP were anxiolytic medication, automatic behavior, bipolar disorders, physical disease, hypnopompic hallucinations, nonrestorative sleep, and nocturnal leg cramps.
Conclusions: SP is less common in the general population than was previously reported. This study indicates that the disorder is often associated with a mental disorder. Users of anxiolytic medication were nearly five times as likely to report SP, even after we controlled for possible effects of mental and sleep disorders.