Poor sleep quality is associated with blunted baroreflex sensitivity during stress cardiovascular reactivity in older adults

Objectives: Poor sleep quality may contribute to autonomic dysfunction in older adults, but evidence regarding its effect on stress-associated baroreflex sensitivity (BRS), an important physiological indicator, is limited. Methods: data were derived from the MIDUS 3 Biomarker Project (2017-2022). Stress-associated BRS was measured using the sequence method while participants are taking a math-task (used as a psychological stressor) to solve in prespecified limited time. Sleep quality was assessed via the Pittsburgh Sleep Quality Index (PSQI). Multiple linear regression analyses were conducted to examine the association between sleep quality and stress-associated BRS, adjusting for insulin resistance (measured using HOMA-IR), age, sex, smoking history, physical activity, systolic blood pressure (SBP) measured during stress, body mass index (BMI), total cholesterol-to-HDL ratio, medications, respiratory rate measured during stress, and anxiety and depression (measured as a composite of general distress-anxiety and depression scales from Mood and Symptom Questionnaire (MASQ)). Log transformation was applied to BRS values to meet analysis assumptions. Results: The final sample included 401 participants (58.6% female; mean age 63.9 ± 8.6 years). In crude analysis, sleep quality was not associated with BRS. After adjustment, poorer sleep quality was significantly associated with impaired stress-associated BRS (Beta = -0.121; 95% CI: [-0.233 to -0.008], P = 0.035). In addition, higher SBP was the only covariate associated with significant decrease in BRS (Beta = -0.117; 95% CI: [-0.214 to -0.019], P = 0.019). Mediation analysis revealed that heart rate fully mediated the association between sleep quality and BRS, with near-significant total association and significant indirect association (estimate = -0.01; 95% CI: [-0.0160 to -0.003], P = 0.003). Conclusion: Poor sleep quality is associated with impaired stress-associated BRS in older adults, with important mediating role for autonomic arousal represented by heart rate.