Prevalence of insomnia and associated factors in South Korea.
BACKGROUND
In Western countries, insomnia is associated with daytime impaired functioning, as well as physical and psychiatric illnesses. However, little information exists on insomnia in Asian countries. This study investigates the prevalence and correlates of insomnia in the general population of South Korea.


METHODS
A representative sample of the South Korean general population composed of 3719 noninstitutionalized individuals aged 15 years or older were interviewed by telephone using the Sleep-EVAL system. The participation rate was 91.4%. The interviews covered sleep habits, sleep symptomatology, physical and psychiatric illnesses. DSM-IV sleep and psychiatric disorder diagnoses were also assessed.


RESULTS
Insomnia symptoms occurring at least three nights per week were reported by 17.0% of the sample; difficulty initiating sleep (DIS) was mentioned by 4.0% of the sample, difficulty maintaining sleep (DMS) by 11.5%, early morning awakenings (EMA) by 1.8%, and nonrestorative sleep (NRS) by 4.7% of the sample. DSM-IV insomnia disorder diagnoses were found in 5% of the sample. Over 50% of subjects with insomnia symptoms reported important daytime consequences and another 20% reported mild or moderate consequences. However, the proportion of insomnia subjects seeking medical help for their sleep problems was very low (6.8%).


CONCLUSIONS
As in Western countries, insomnia is widespread in South Korea, affecting nearly one in five individuals. Many of them would benefit from medical help; however, few insomnia subjects are consulting for this problem. An educational effort is needed for both the general population and the physicians.
Ohayon
Maurice M
MM
Stanford Sleep Epidemiology Research Center, School of Medicine, Stanford University, Suite 3301, 401 Quarry Road, Stanford, CA 4305, USA. mrcohayon@aol.com
Hong
Seung-Chul
SC
D000293:Adolescent; D000328:Adult; D000368:Aged; D003863:Depression / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012044:Regression Analysis; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology* / Q000523:psychology