Sleep paralysis in Chinese: ghost oppression phenomenon in Hong Kong.

Despite reports of wide variation in the prevalence of sleep paralysis among different ethnic groups, there has never been any study in Chinese. In Hong Kong, a condition known as ghost oppression is descriptively identical to sleep paralysis. To examine this phenomenon, the response of 603 undergraduate students to a questionnaire were analyzed. Thirty-seven percent had experienced at least one attack of ghost oppression. There was no sex difference in the prevalence, and the peak age of onset was at the range of 17-19 for both sexes. A strong familial association was found and 20% of subjects reported a positive family history. Over one sixth of the subjects identified sleep disruption and stress as precipitating events.