Gender differences in insomnia--a study in the Hong Kong Chinese population

OBJECTIVE: To study the epidemiology of insomnia in the adult Chinese population in Hong Kong and to examine the potential gender-related demographic and lifestyle factors in insomnia. METHODS: A population study via random telephone survey with a structured questionnaire was carried out for noninstitutionalized Chinese adults aged 18-65 by trained lay interviewers. The questionnaire included demographic data, sleep habits and problems, insomnia symptoms and lifestyle questions. RESULTS: A total of 9851 subjects (46.4% male; 53.6% female) were included in the final analysis. The overall prevalence of Hong Kong Chinese as suffering from insomnia during the preceding month (with a frequency of sleep disturbance of at least three times per week) was 11.9% (95% CI 11.2-12.6), including difficulty in initiating sleep (DIS) (4.5%; 95% CI 4.1-5.0), difficulty in maintaining sleep (DMS) (6.9%; 95% CI 6.4-7.5) and early morning awakening (EMA) (4.0%; 95% CI 3.6-4.4). Females were about 1.6 times at higher risk for insomnia than males. The prevalence of insomnia was also shown to increase with age. Multivariate analysis showed that unemployment, lower economic status, alcohol consumption, regular medication and psychiatric disturbance were all associated with higher risks of insomnia in both sexes. Furthermore, lower education level and being retired was associated with a higher risk of insomnia in males, but being a housewife, divorced/widowed, and complaining of a nocturnal noisy environment were associated with a higher risk of insomnia in females. Among all these factors, psychiatric disturbance was the most influential risk factor for insomnia in both sexes. The reasons for gender differences of insomnia may include their differences in the prevalence of psychiatric morbidities, symptom endorsement, gonadal steroids, sociocultural factors and coping strategies. CONCLUSIONS: Overall, 11.9% of the Hong Kong Chinese adult population complained of frequent insomnia in the preceding month. There was a higher prevalence of insomnia in females. Although there were common risk factors for insomnia in both sexes, there existed gender-specific risk factors.