Somatic symptoms and psychological characteristics associated with insomnia in postmenopausal women

The aim of the study was to assess the association of sleep disturbance with psychological characteristics, somatic symptoms and previously identified risk factors. Data were from 148,938 postmenopausal women enrolled in The Women's Health Initiative who provided cross-sectional information about psychological characteristics, somatic symptoms and the character of their sleep. Overall sleep quality was based on the Women's Health Initiative Insomnia Rating Scale (WHI IRS), a measure that assessed five types of sleep disturbance. Three factors accounted for nearly 20% of the variation in the WHI IRS: a scale for somatic symptoms, daytime restlessness and either depression or emotional well-being. Other independently associated factors were night sweats, pain and worry about expressing anger. Several factors that had been linked to sleep disturbance in other studies were found to have at most a weak independent association in this analysis. These included income, education, marital status, activity level, obesity level, hot flashes, coffee drinking and smoking. Factors strongly associated with sleep disturbance in this study deserve further evaluation to determine the reasons for the association and whether the associations suggest possible treatments for sleep disturbance.