0094 Habitual Sleep and Autonomic Function in Humans

Abstract Introduction Insufficient habitual sleep duration and efficiency are commonly experienced in modern society and are associated with cardiovascular disease development. A potential mediator of this relationship may be impairment in cardiovascular regulation via the autonomic nervous system. The purpose of the present study was to assess the relationships between habitual total sleep time (TST), sleep efficiency (SE), muscle sympathetic nerve activity (MSNA), and heart rate variability (HRV) in a robust sample of healthy adults. We hypothesized that shorter TST would be associated with increased sympathetic and decreased parasympathetic activity. Methods A minimum 7 days of at-home, objective actigraphy sleep monitoring was collected in 75 healthy young adults (39 males, 36 females; 24±1 years; 25±1 kg/m2). In each participant, three seated sphygmomanometer recordings were used to determine resting mean arterial blood pressure (MAP). Prior to laboratory testing, participants were asked to refrain from caffeine and exercise for 12 hours, and alcohol for 24 hours. 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. R-R intervals were used to quantify both time (i.e., RMSSD and pNN50) and frequency (high-frequency heart rate variability; HF-HRV) domain HRV parameters. RMSSD and HF-HRV were log-transformed due to non-normal distributions. Results Contrary to our hypothesis, habitual TST was not associated with resting MAP (R=0.173, P=0.137), HR (R=-0.137, P=0.241), MSNA (R=-0.186, P = 0.110), RMSSDlog10 (R=0.085, P=0.468), pNN50 (R=0.043, P=0.711), or HF-HRVlog10 (R=0.019, P=0.869). Similarly, SE was not associated with resting MAP (R=0.112, P=0.339), HR (R=-.037, P=0.751), MSNA (R=-0.033, P = 0.778), RMSSDlog10 (R=-0.006, P=0.956), pNN50 (R= -0.003, P=0.983), or HF-HRV (R=-0.028, P=0.810). Conclusion Our findings do not support a relationship between habitual TST or SE and measures of autonomic nervous system activity in healthy adults. However, a more pronounced effect may be observed in populations with established sleep disorders such as insomnia and obstructive sleep apnea. Further research is necessary to establish the independent effect of objective sleep quantity and quality on autonomic control in these populations. Support (if any) NIH AA-024892