Heart Rate Variability During Sleep-Related Wake Phases in REM Sleep Behavior Disorder

Parisa Sattar1, Elisa Facchini2, Giulia Baldazzi3, Nicla Mandas4, Elisa Casaglia5, Michela Figorilli2, Laura Giorgetti6, Pietro Mattioli7, Dario Arnaldi8, Monica Puligheddu9, Danilo Pani10
1Department of Medical Sciences and Public Health, Sleep Disorder Research Center, University of Caglairi; Department of Electrical and Electronic Engineering, University of Cagliari, 2Department of Medical Sciences and Public Health, Sleep Disorder Research Center, University of Caglairi, 3DIEE, University of Cagliari;, 4The Hadron Academy, IUSS, Pavia; DIEE, University of Cagliari, 5Department of Medical Sciences and Public Health, Sleep Disorder Research Center, University of Cagliari, 6Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), Clinical Neurology, University of Genoa, 7Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI),Clinical Neurology, University of Genoa, 8Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI),Clinical Neurology, Univer-sity of Genoa, 9Department of Medical Sciences and Public Health, Sleep Disorder Research Center, University of Cagliari, Cagliari, Italy, 10DIEE - University of Cagliari

Abstract

Aims: Autonomic dysfunction can be observed in people with neuro-degenerative diseases (ND), and heart rate variability (HRV) is frequently adopted to assess it. Indeed, in the literature, a decrease in HRV was observed in individuals with ND, when it was evaluated during sleep stages. Rapid eye movement (REM) sleep behavior disorder (RBD) is widely accepted as a prodromal symptom of alpha-synucleinopathies, a group of neurodegenerative disorders encompassing Parkinson's disease (PD). As such, HRV during the 24-hours or during sleep is being investigated as a potential digital biomarker for these conditions. In this study, we focused on the awake phases immediately before and after sleep, which represents more controlled conditions than 24h recordings without the burden of sleep stag-ing. Thus, we investigated autonomic imbalance in idiopathic RBD (RBDid) and PD with RBD (RBDpd), and unaffected people (CG), during such wake phases. Methods: The dataset consisted of 18 CG, 20 RBDid, and 20 RBDpd participants, who underwent polysomnographic exams with at least six-hours of sleep. For each participant, a 5-min ECG signal was obtained in the two awake phases, and processed to extract different indexes from time, frequency, and non-linear domains. Non-parametric statistical analysis was used, for each group separately, to assess differences between the two wake stages. Results: Significant differences were found in time and frequency domain indexes in RBDpd and RBDid groups, highlighting an HRV increase in the wake stage immediately after sleep, as compared to the wake stage before sleep onset (p<0.05 to p<0.0001). Similarly, in the same groups, a significant reduction in nonlinear indexes was found during the last wake stage (p<0.01), indicating an altered autonomic regulation in the same groups w.r.t. CG. Conclusions: Results indicate that RBD may cause an increase in para-sympathetic activities, with similar behavior along with diagnosed PD or not.