A POPULATION STUDY ON RISK-FACTORS FOR INSOMNIA AMONG ADULT JAPANESE WOMEN - A POSSIBLE EFFECT OF ROAD TRAFFIC VOLUME

In an effort to identify risk factors fur insomnia and determine the c ontribution of nighttime road traffic volume to insomnia in the genera l population, a questionnaire survey was carried out among 3,600 adult Japanese women living in eight urban residential areas. The crude pre valence rate of insomnia was 11.2%. Multivariate analysis revealed tha t aging, living with a child/children aged six or younger, undergoing medical treatment, experiencing major life events, having an irregular bedtime, having a sleep apnealike symptom, and living near a road wit h a heavy volume of traffic are risk factors for insomnia. Taking into account other risk factors, there was a level-response relationship b etween the nighttime traffic volume of main roads and the risk of inso mnia in the subjects living in the zones 0-20 m from these roads. Thes e results suggest that road traffic noise raises the sound level in be drooms in such zones, and consequently the prevalence rate of insomnia among the residents, and that noise-induced insomnia is an important public health problem, at least in highly urbanized areas. To confirm this, a further study on noise exposure is needed.