Abstract 24: Actigraphy-Measured Sleep Irregularity Increases the Risk of Incident Cardiovascular Disease and Cardiovascular Mortality in Older Women

Background: Cardiovascular disease (CVD) is the leading cause of death for U.S. women. Our understanding of how poor sleep health contributes to CVD is limited by reliance on cross-sectional studies, self-reported sleep measures, and predominately non-Hispanic white samples. Our objective was to prospectively investigate actigraphy-measured sleep health and incident CVD and CVD mortality in a cohort of older multiethnic women. Methods: Women (n=3,992; mean age: 78.5 years, 33% African American, 17% Hispanic/Latino) enrolled in the Women’s Health Initiative OPACH (Objective Physical Activity and Cardiovascular Health) study wore an Actigraph GT3X+ accelerometer for 7 days in May 2012-April 2014 and were followed through February 2022 for physician-adjudicated incident CVD (definition in Table footnote) and CVD mortality. Sleep duration, timing, efficiency, irregularity, and continuity were derived from accelerometers (definition in Table footnote). Women with prior CVD at baseline were excluded from analyses. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Minimally adjusted models included age, race and ethnicity. Models were additionally adjusted for education, smoking, alcohol consumption, comorbid conditions, self-rated health, and CVD risk factors. Results: Over a median of 8.3 years of follow-up, 636 incident CVD cases occurred, including 395 CVD deaths. In minimally adjusted models, longer sleep duration, greater sleep irregularity, and more wake after sleep onset were associated with increased CVD risk (Table 1). In models further adjusted for CVD risk factors, the HR (95% CI) for a 60-minute increase in sleep irregularity was 1.18 (1.01-1.37) for incident CVD and 1.30 (1.07-1.58) for CVD mortality. Conclusions: Greater sleep irregularity was associated with higher risk of incident CVD and CVD mortality in a diverse cohort of older women. These results support the importance of maintaining regular sleep for cardiovascular health.