Table 3.

Linear mixed model analysis of fixed effects of factors (tonic/phasic RSWA, sleep stage) on heart rate variability parameters in participants with iRBD.

	Association of Tonic RSWA with HRV				Association of Phasic RSWA with HRV
	B	95% CI Boundary		P	B	95% CI Boundary		P
		Lower	Upper			Lower	Upper
Normalized LF
RSWA	−0.00263	−0.00437	−0.00089	.004*	0.00141	−0.00267	0.00550	.490
Sleep stage				.003*				.003*
W	0 (ref)				0 (ref)
N2	−0.08274	−0.16309	−0.00239		−0.01005	−0.07897	0.05887
R	0.09869	0.01304	0.18434		0.11306	0.04698	0.17915
RSWA × sleep stage				.016*
W	0 (ref)
N2	0.00271	−0.00437	0.00453
R	0.00062	0.00090	0.00255
Normalized HF
RSWA	0.00263	0.00089	0.00437	.004*	0.00141	−0.00550	0.00267	.490
Sleep stage				.003*				.003*
W	0 (ref)				0 (ref)
N2	0.08274	0.00239	0.16309		−0.01005	−0.05887	0.07897
R	−0.09869	−0.18434	−0.01304		0.11306	−0.17915	−0.04698
RSWA × sleep stage				.016*
W	0 (ref)
N2	−0.00271	−0.00453	0.00437
R	−0.00062	−0.00255	−0.00090
LF/HF ratio (L)
RSWA	−0.12924	−0.02132	−0.00453	.003*	0.00531	−0.01453	0.02514	.593
Sleep stage				.003*				.004*
W	0 (ref)				0 (ref)
N2	−0.40574	−0.80675	−0.00472		−0.05614	−0.39795	0.28568
R	0.49382	0.04655	0.94109		0.56396	0.21876	0.90916
RSWA × sleep stage				.020*
W	0 (ref)
N2	0.01305	0.00398	0.02211
R	0.00302	−0.00705	0.01309

(L) Parameters were log-transformed before performing linear mixed model analysis. *P < 0.05. HF = high frequency, LF = low frequency, RMSSD = root mean square difference of successive R-R intervals, RSWA = rapid eye movement sleep without atonia, SDNN = standard deviation of R-R intervals.