Introduction: Short sleep duration has been associated with increased risk of cardiovascular and cerebrovascular disease (CVD), cognitive impairment (CI) and mortality. However, the role of sleep duration in predicting mortality in the context of CVD and CI is still not well-understood.
Hypothesis: Short sleep duration is a key effect modifier of the relationship between CI associated with CVD and all-cause mortality.
Methods: We addressed this hypothesis in the Penn State Adult Cohort, a random, general population sample of 1,741 middle-aged adults who were studied in the sleep lab and followed-up for 15y. An in-lab, 8-hour polysomnography was performed to ascertain sleep duration. CI associated with CVD was defined by the presence of hypertension, diabetes, heart disease and/or stroke with impaired higher-order, executive cognitive functioning, including slow processing speed. We tested the interaction between sleep duration and CI associated with CVD on all-cause mortality with multiple logistic regression while adjusting for sex, age, race, obesity, smoking, cholesterol, depression, insomnia, dementia, and sleep apnea.
Results: The odds of mortality associated with CI-alone, CVD-alone, and CI associated with CVD were 1.3 (95% CI: 0.7-2.4), 1.7 (95% CI: 1.1-2.8), and 4.6 (95% CI: 2.8-7.7), respectively. As shown in Figure 1, the interaction between CI associated with CVD and sleep duration was significant (p < .01), indicating that the probability of mortality increased significantly as a function of shorter sleep duration in individuals with CI associated with CVD.
Conclusion: We found that objective sleep duration modifies the relationship between CI associated with CVD and all-cause mortality in a dose-response manner. Short sleep duration in individuals with probable vascular cognitive impairment (VCI) may serve as a biomarker of the severity of central autonomic dysfunction. Future studies should examine whether improving sleep reduces the odds of mortality in individuals with VCI.