Health Disparities
Sleep regularity and other sleep dimensions in relation to incident cardiovascular disease among middle- to older-aged US women Symielle A. Gaston* Symielle Gaston Gaston Gaston Gaston Gaston National Institute of Environmental Health Sciences
Sleep health is increasingly recognized as a pillar of cardiovascular health. Yet, few studies have examined multiple sleep dimensions, including regularity, in relation to cardiovascular disease (CVD). Also, few have assessed racial-ethnic differences in women. We investigated multiple sleep dimensions in relation to incident CVD overall and by race-ethnicity among 42,542 women (mean age 55±8.9 years; 86% non-Hispanic White, 8.4% non-Hispanic Black [NHB], 3.3% Latina, 2.6% another race-ethnicity group) in the Sister Study without prior CVD. At enrollment (2003–2009), participants reported bed and wake times over 7 days, from which we derived mean sleep duration (hours), duration regularity (SD of durations), mean sleep timing (sleep midpoint), timing regularity (SD of midpoints), and social jet lag (midpointnon-workdays – midpointworkdays). Insomnia symptoms (IS: difficulty falling/staying asleep ≥3 nights/week) and frequent napping (≥3 times/week) were also reported (yes vs. no). Incident CVD (i.e., ischemic heart disease, heart failure, myocardial infarction, stroke, or related procedures) was captured through October 2022. Cox proportional hazards models estimated associations (HRs [95% CIs]) between multiple sleep dimensions simultaneously (given weak correlations: |r|≤0.10) and CVD, adjusting for relevant confounders. Effect modification (EM) was tested with cross-product terms. Over a median follow-up of 14.4 years, 3,132 incident CVD events occurred. With small variation across participants, mean sleep duration was 7.5±1.1 hours and mean sleep midpoint was 2:24 (1:06–3:42) AM. IS and frequent napping were more prevalent among CVD cases and NHB women. After adjustment, only IS were associated with higher CVD risk, observed only among NHB women (HR=1.81 [1.12–2.92] vs. HRrange: 0.71-1.05; pEM=0.02). IS—not sleep regularity—emerged as a key CVD risk factor, particularly among Black women, highlighting a potential target for reducing disparities in CVD risk.