title: Longitudinal changes in insomnia status and incidence of physical, emotional, or mixed impairment in postmenopausal women participating in the Women's Health Initiative (WHI) study.
abstract: OBJECTIVE
  We assessed prevalence and correlates of insomnia; associations between changes in insomnia with incidence of physical, emotional, and mixed impairments (PI, EI, and MI, respectively); and age as a moderator in these relationships.
  
  
  METHODS
  The Women's Health Initiative (WHI) clinical trial (CT) and observational study (OS) cohorts with 1- and 3-year follow-ups, respectively, were studied. Participants included 39,864 CT and 53,668 OS postmenopausal women free of PI or EI at baseline. Insomnia Rating Scale (IRS), with a cutoff score of ≥9 indicated insomnia. Normal-Normal, Abnormal-Abnormal, Normal-Abnormal, and Abnormal-Normal categories indicated change in insomnia over time. PI, EI, and MI were constructed using Short Form-36 (SF-36) Physical and Emotional subscales (cutoff ≤60) and the modified Center for Epidemiological Studies Depression scale (cutoff ≤0.06).
  
  
  RESULTS
  Among 93,532 women, 24.5% had insomnia at baseline. The highest odds ratios (ORs) for impairments were found in the Normal-Abnormal and Abnormal-Abnormal categories. In the CT cohort, Normal-Abnormal category, ORs were 1.86 (95% CI = 1.57-2.20) for PI, 4.11 (95% CI = 3.59-4.72) for EI, and 6.37 (95% CI = 4.65-8.74) for MI. Respective ORs for the OS cohort were 1.70 (95% CI = 1.51-1.89), 3.80 (95% CI = 3.39-4.25), and 4.41 (95% CI = 3.56-5.46). Interactions between changes in insomnia and age showed distinct albeit nonsignificant patterns.
  
  
  CONCLUSIONS
  The results suggest that exposure to insomnia increases vulnerability to impairment. Future studies are needed to understand the directionality of these relationships.
authors.affiliation: Faculty of Health Science and Social Welfare, University of Haifa, Israel. Electronic address: oleg.zaslavsky@fulbrightmail.org.
authors.forename: Oleg
authors.initials: O
authors.lastname: Zaslavsky
authors.affiliation: Division of Epidemiology, School of Medicine, University of California San Diego, CA, United States; Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, United States.
authors.forename: Andrea Z
authors.initials: AZ
authors.lastname: LaCroix
authors.affiliation: Department of Preventive Medicine, Program in Public Health, School of Medicine, Stony Brook University, NY, United States.
authors.forename: Lauren
authors.initials: L
authors.lastname: Hale
authors.affiliation: Division of General Internal Medicine, University of Pittsburgh, PA, United States.
authors.forename: Hilary
authors.initials: H
authors.lastname: Tindle
authors.affiliation: Faculty of Health Science and Social Welfare, University of Haifa, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Shochat
mesh_terms: D000342:Affective Symptoms / Q000453:epidemiology*; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D004644:Emotions; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause / Q000523:psychology*; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications* / Q000523:psychology* / Q000628:therapy; D016387:Women's Health
keywords: Functioning; Insomnia; Longitudinal; Older adults; Women's health