Prevalence of risk factors for sleep apnea in Japan: a preliminary report

A final goal of the present study is to estimate the prevalence of sleep apnea in the general population of Japan. As the first step, the detailed questionnaires were sent out to the presumably healthy subjects who underwent regular medical checkups at four hospitals in different cities of Japan. The questionnaires included queries about difficulties in initiating and maintaining sleep, habitual snoring, parasomniac symptoms, excess daytime sleepiness, any present illness, consumptions of cigarettes and alcohol and so on. A total of 3,243 replies were obtained so far (2,029 male and 1,214 female; mean age = 50 years). The results were consistent among the four hospitals, and the prevalences of risk factors were as follows: habitual snoring was reported by 12.8-16.0%, excess daytime sleepiness by 8.1-9.4% and frequent awakenings by 7.3-12.6%, respectively. The prevalence of systemic hypertension ranged from 5.3% to 12.9%. Polysomnographic studies are being performed on the possible cases of sleep apnea who were sorted out by the questionnaires.