Rem Sleep Behavior Disorder in Healthy Subjects, Autonomic Cardiovascular Regulation Varies Considerably with Sleep Stage. Non-rapid Eye Movement (nrem) Sleep

IN HEALTHY SUBJECTS, AUTONOMIC CARDIOVASCULAR REGULATION VARIES CONSIDERABLY WITH SLEEP STAGE. NON-RAPID EYE MOVEMENT (NREM) SLEEP is characterized by relative autonomic stability, a dominance of parasympathetic influences to the heart, and a reduction in sympathetic efferent vasomotor tone, all of which translate into a stable low heart rate and low blood pressure.1,2 In contrast, rapid eye movement (REM) sleep is a state of autonomic instability, dominated by remarkable fluctuations between parasympathetic and sympathetic influences, which produce marked sudden changes in heart rate and blood pressure.1-3 In addition, respiration becomes shallower and more frequent in response to REM sleep.4,5 Spectral analysis of RR variability has consistently revealed that, in normal subjects, different rhythms dominate in NREM and REM sleep: a shift toward the respiratory-mediated highfrequency components (HF, ~0.25 Hz) of R-R variability characterizes NREM sleep, whereas the cardiovascular excitation and instability of REM sleep is reflected by a significant increase of the low-frequency components (LF, ~0.1 Hz).6,7 REM sleep behavior disorder (RBD) is a parasomnia occurring during REM sleep only, characterized by a loss of the characteristic skeletal muscle atonia and the presence of complex motor activity in association with dream mentation.8,9 Patients with RBD frequently evolve toward neurodegenerative disorders, especially Parkinson disease and dementia with Lewy bodies,8-10 both known to be associated with dysautonomia.11,12 Preliminary studies have revealed a blunted heart rate response associated with body movements during sleep in idiopathic RBD.13,14 The objective of this study was to assess autonomic cardiac regulation and respiratory responses during sleep in subjects with idiopathic RBD, compared with controls, using spectral analysis of R-R variability and respiration variability. We tested the hypothesis that REM sleep-related cardiac and respiratory responses are altered in subjects with idiopathic RBD.