Autonomic Dysfunction in REM Sleep Disorder: The Role of Respiration in HRV Analysis

Autonomic nervous system (ANS) has been suggested often associated with the isolated rapid eye movement (REM) sleep behavior disorder (iRBD), with iRBD, and heart rate variability (HRV) is a commonly used tool to assess it. However, the accuracy of HRV is heavily influenced by respiratory rate (RespR), potentially causing misinterpretation of frequency domain HRV indices. This study compares sleep-related ANS function between iRBD patients and a control group (CG) using respiratory-adjusted HRV spectral analysis. It involves 20 iRBD and 20 CG participants in each group, from which five-minute ECG signal epochs during N2, N3, and REM sleep phases are analyzed. RespR were estimated from ECG-derived respiratory signals. Both low and high frequency bands definition for HRV analysis were redefined using the RespR. The results indicate significant differences in HRV parameters between iRBD and CG subjects during REM sleep, highlighting disrupted autonomic regulation in iRBD. This finding is also evident in non-REM phases, thus emphasizing the need to incorporate RespR in HRV analysis, especially in sleep-related studies, for a comprehensive understanding of autonomic dysfunction.