Neuroendocrine dysfunction in patients with postural orthostatic tachycardia syndrome

Abstract

s / Autonomic Neuroscience: Basic and Clinical 163 (2011) 1–133 96 (Vanderbilt University -Medicine, United States), M.G. Farley (Vanderbilt University -Medicine, United States), B.K. Black (Vanderbilt University -Medicine, United States), I. Biaggioni (Vanderbilt University -Medicine & Pharmacology, United States), D. Robertson (Vanderbilt University -Medicine, Pharmacology & Neurology, United States), S.R. Raj (Vanderbilt University -Medicine & Pharmacology, United States) Background: Patients with postural tachycardia syndrome (POTS; heart rate [HR] increase >30 bpm on standing) have many noncardiac symptoms, including sleep disturbances. We have previously reported that patients with POTS have excessive daytime somnolence and a significant reduction in sleep quality. There are no published data assessing “real time” sleep quality in POTS. We used 1 week of objective activity monitoring (actigraphy) to test the null hypothesis that there was no difference in the sleep quality between POTS and controls. Methods: Female patients with POTS (n=32; 36±2 years) and healthy control subjects (n=30; 32±2 years) wore an activity watch for 1 week. They also recorded sleep/wake times in a diary, and rated the quality of their sleep and morning fatigue. Data were analyzed using a Student's t-test and are presented as mean±SEM. Results: Compared with control subjects, patients with POTS reported more restless nights of sleep (54±5% vs. 22±4%; P<0.001) and greater morning fatigue (79±4% vs. 38±5%; P<0.001). There was no difference between the 2 groups in total sleep time (369±13 min vs. 374±11 min; P=0.8), however POTS patients had longer subjective sleep onset latency (60±12 min vs. 13±1 min; P=0.001), and more nocturnal awakenings (2.8±0.3/night vs. 1.4±0.2/night; P<0.001). Overall, sleep efficiency was decreased in patients with POTS (72±3% vs. 79±1%; P=0.011). Conclusions: Patients with POTS report greater morning fatigue, more frequent nocturnal awakenings, and restless sleep as compared with healthy subjects, despite comparable quantity of total sleep time. Actigraphy shows that POTS patients are more mobile at night, awaken more frequently and sleep less efficiently. The etiology for poor sleep in POTS patients remains unclear. Further studies with polysomnography are needed to characterize, and ultimately treat postural tachycardia syndrome related sleep problems to help improve the sleep quality of these patients.