Epidemiological study of nightmare and sleep paralysis among Japanese adolescents

In this study, we have elucidated the prevalence of and factors associated with nightmares and sleep paralysis in Japanese adolescents. We conducted a survey of first-year senior high school students by employing self-administered questionnaires about nightmare and sleep paralysis. All the subjects were first-year students (1164) from three private high schools. The responses of the remaining 916 subjects (568 boys and 348 girls) were considered valid. We found that in Japanese adolescents, the current prevalence of nightmares is 27.4%, and that of sleep paralysis is 7.2%. The lifetime prevalence of sleep paralysis is 30.4%. Results of the multiple logistic regression analysis revealed factors associated with nightmare and sleep paralysis. With regard to nightmares, the adjusted odds ratios for female gender, bedtime after 12 am, wake up time before 6:30 am, difficulty maintaining sleep or early morning awakening, daily tea drinking, poor mental health, and presence of sleep paralysis were significantly high. With regard to sleep paralysis, the adjusted odds ratios for 30 min or more of sleep latency, less than 6 h of sleep duration, presence of naps, and presence of nightmares were significantly high. These results reveal that nightmare and sleep paralysis are prevalent problems among adolescents as well as adults. Moreover, these conditions are associated with factors of mental health and insomnia, and that these factors are associated with each other. Such associations should be considered in the prevention and treatment of nightmares and sleep paralysis among adolescents.