Habitual Sleep and Muscle Sympathetic Nerve Activity in Humans

Short habitual sleep duration and inadequate sleep effciency are associated with poor cardiovascular health. Although a potential mediator of this relationship is augmented sympathetic activity, only one study to date has assessed the relationship between objectively measured habitual sleep duration and direct muscle sympathetic nerve activity (MSNA) in humans. Moreover, the proportion of resting MSNA that can be independently explained by habitual sleep while controlling for other key variables remains unknown. The purpose of the present study was to assess the independent relationship between total sleep time (TST), sleep effciency (SE), and MSNA in a large population of young males and females. We hypothesized that short TST and low SE would be associated with elevated MSNA and blood pressure. A minimum 7 days of at-home, objective actigraphy sleep monitoring was collected in 66 healthy young adults (35 males, 31 females; 24±1 years; 26±1 kg/m 2 ). In each participant, the average of three seated brachial blood pressures was recorded and used to determine resting mean arterial blood pressure (MAP). All participants underwent an autonomic function test that simultaneously assessed heart rate (HR, electrocardiogram), beat-to-beat blood pressure (finger plethysmography) and MSNA (microneurography) during 10 minutes of quiet rest. Resting MAP (83±1 mmHg), HR (64±1 beats/min) and MSNA (19±1 bursts/min) were normally distributed. Habitual TST was significantly correlated with MSNA (r=-0.265, p=0.032), but was not associated with resting MAP (r=-0.153, p=0.219) or HR (r=-0.205, p=0.098). SE was not associated with any of the outcome variables (all p>0.25). Multiple regression was used to test the independent relationship between TST, MAP, HR, and MSNA while accounting for effects of age, sex, and body mass index (BMI). The regression model significantly predicted MAP (R 2 =0.253, p=0.001) and MSNA (R 2 =.211, p=0.005), but not HR (R 2 =.047, p=0.560). TST did not independently explain any additional variance in MAP (ΔR 2 =0.004, p=0.562) beyond that ascribed to the effects of age, sex, and BMI. In contrast, TST independently explained an additional 5% of the variance in MSNA (ΔR 2 =0.053, p=0.048). In a large sample of healthy young males and females, our results indicate that habitual TST explains only a minor proportion of the observed variance in resting MSNA between participants. NIH (AA-024892). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.