Sleep duration-associated CV risk dependent on sex and race
Sleep duration and risk of incident stroke by age, sex, and race The REGARDS study
Introduction and methods
Sleep duration may contribute to risk of stroke [1] and this relationship may be dependent on demographic factors, such as age, sex and race [2]. Previous data suggest that short sleep duration partially modifies the relationship between race (black vs. white adults) and incident stroke symptoms [3], and that short or long sleep duration may be related to excess risk of poor cardiometabolic risk status among black adults [4-9]. However, only few studies assessed race differences on the effect of sleep duration on risk of stroke. This study investigated the sleep duration-stroke relationship and determined whether age, sex, race and combinations of these factors modified this relationship.
The Reasons for Geographic and Racial Differences in Stroke REGARDS (REGARDS) study is a US-population based cohort investigating stroke incidence and mortality among 30,239 black and white participants aged ≥45 years. This subanalysis of the REGARDS study (n=16,733) included subjects that completed an ancillary sleep module and who were free of physician-diagnosed stroke and obstructive sleep apnea at the time of sleep module completion.
Habitual sleep duration was assessed based on questions regarding their habitual sleep duration on weekdays and weekends. Participants were categorized based on a weighted average of the duration on weekdays and weekends: <6 hours (short duration), 6.0 - 6.9, 7.0 - 8.9 (reference group) and ≥9 hours (long duration). Stroke events were identified every 6 months via telephone interview and medical records associated with these events were retrieved and physician-adjudicated.
Main results
- There was no interaction between sleep duration and age (P=0.92) or sleep duration and sex in the demographic model (P=0.31).
- After multivariable adjustment, an interaction was observed between sleep duration and race (P=0.018).
- Short sleep duration was associated with reduced risk for stroke in black participants (HR: 0.48, 95%CI: 0.28–0.83, P<0.05) and with increased risk for stroke in white participants (HR: 1.64,95%CI: 1.09–2.45, P<0.05). This increased risk of stroke in white individuals was attenuated after adjustment for risk factors of stroke (HR: 1.40, 95%CI: 0.91–2.13).
- After multivariable adjustment, there was an interaction between sleep duration and race–sex groups (P=0.028).
- Short sleep duration was associated with decreased risk for stroke in black men (HR: 0.20, 95%CI: 0.06–0.66, P<0.05) and long sleep duration was associated with increased risk for stroke in white men (HR: 1.96, 95%CI: 1.25–3.09, P<0.05), which remained after adjustment for stroke risk factors and hypertension.
- Interaction between sleep duration and race-sex group became non-significant (P=0.074) when participants at high risk for sleep-disordered breathing were omitted from analysis.
Conclusion
Short sleep duration (<6 hours) was associated with decreased risk of incident stroke in black men, whereas long sleep duration (≥9 hours) was associated with increased risk for stroke in white men, suggesting that short and long sleep duration may have differing consequences depending on race and sex. These data underscore the need for mechanistic, longitudinal research of the sleep duration-stroke relationship by demographic subgroups. Furthermore, it may be clinically advisable to assess and monitor middle-aged adult patient with long sleep duration, particularly white men, for CV risk.
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