[Epidemiologic research on insomnia in the general Japanese populations]

This paper reviews epidemiologic research on insomnia of the general Japanese populations in the last 10 years. Nationwide studies, 3 for adults and 2 for adolescents, were conducted in communities to estimate prevalence of insomnia and examine associated factors with insomnia. For adults, prevalence of insomnia was estimated of 17.3 to 22.3% for men and 20.5 to 21.5% for women. The associated factors were identified: increasing age, gender, being unemployed, poor health status, being psychological stressed, less physical activities, and use of hypnotic medications and nightcap. For adolescents, they were 23.3% for boys and 23.7% for girls. Gender, poor mental health, smoking, drinking, college-bound, and lifestyle (e.g., not eating breakfast, late bedtime, not involved in extramural activities) were suggested as the associated factors. These findings have contributed to enhance the social recognition about the importance of insomnia for the general population in Japan.