Goal: This work aims at characterizing autonomic dysfunction in RBD subjects using heart rate variability (HRV) indexes computed from ECG recordings during polysomnographic studies. Results: RR variance (σ 2 ) is significantly lower in RBD both in N1 (p=0.018) and N3 (p=0.035) sleep stages. High frequency (HF) power, related to vagal control, shows a statistically significant difference between the two populations in N3 (p=0.008) and REM (p=0.028), with higher medians in the healthy subjects. Median HF power in healthy subjects reduces while moving from NREM to REM stage, whereas medians of RBD group have a similar order of magnitude in all sleep stages, always smaller than healthy controls. Conclusions: Results point at an overall reduction of HRV in RBD when compared to healthy controls, supported by the observed lower σ 2 and HF power, mainly in N3 and REM sleep stages. As expected, sympathetic activation in REM stage is observed in the control group, whereas RBD subjects show higher normalized HF power during sleep, possibly indicating an impaired sympathetic activation in RBD subjects.