Prevalence and pathologic associations of sleep paralysis in the general population.
Neurology April 12, 1999 M M Ohayon, J Zulley, C Guilleminault et al.
About 6.2% of the general population in Germany and Italy has experienced at least one episode of sleep paralysis, with 0.8% experiencing severe episodes (at least one per week). Sleep paralysis is less common than earlier small-sample studies suggested. The condition is often linked to mental disorders; users of anxiolytic medication were nearly five times as likely to report sleep paralysis, even after accounting for mental and sleep disorders. Other predictive factors include automatic behavior, bipolar disorders, physical disease, hypnopompic hallucinations, nonrestorative sleep, and nocturnal leg cramps.