Racial/ethnic disparities in women's sleep duration, continuity, and quality, and their statistical mediators: Study of Women's Health Across the Nation.

Study Objectives To describe racial/ethnic differences in sleep duration, continuity, and perceived sleep quality in postmenopausal women and to identify statistical mediators of differences in sleep characteristics. Methods Recruited from the observational Study of Women's Health Across the Nation (SWAN), 1,203 (548 white, 303 black, 147 Chinese, 132 Japanese, and 73 Hispanic; mean age 65 years, 97% postmenopausal) women participated in a week-long actigraphy and daily diary study in 2013-2015. Actigraphic measures of sleep duration and wake after sleep onset (WASO), and diary-rated sleep quality were averaged across the week. Candidate mediators included health-related variables; stress; and emotional well-being assessed up to 13 times across 18 years from baseline to sleep study. Results Whites slept longer than other groups; the significant mediators were concurrent financial hardship and increasing number of stressors for Hispanics or Japanese versus whites. Whites had less WASO than blacks and Hispanics; significant mediators were concurrent number of health problems, physical inactivity, waist circumference, vasomotor symptoms, number of life stressors, and financial hardship, and increasing number of health problems from baseline to sleep study. Whites reported better sleep quality than blacks, Chinese, and Japanese; significant mediators were concurrent physical inactivity, vasomotor symptoms, positive affect, and depressive symptoms. Conclusions Sleep differences between blacks or Hispanics versus whites were mediated by health problems, number of stressors, and financial hardship, whereas sleep differences between Chinese or Japanese versus whites were mediated by emotional well-being. This is the first study using formal mediational approaches.