. 2020 Aug 5;14(6):606–620. doi: 10.4162/nrp.2020.14.6.606

Table 3. Changes in nocturnal heart rate variability parameters.

Variables		Session	180	P-value	Time × session	210	P-value	Time × session	240	P-value	Time × session
Time domain
	rMSSD	N-FS	−3.94 ± 4.99	0.104	0.060	−2.61 ± 5.64	0.065	0.043^*	2.46 ± 5.91	0.798	0.842
	rMSSD	FS	8.69 ± 4.52	0.104	0.060	13.01 ± 3.59	0.065	0.043^*	4.19 ± 4.60	0.798	0.842
	pNN50	N-FS	−2.01 ± 3.78	0.231	0.187	−0.99 ± 4.46	0.135	0.130	4.32 ± 4.78	0.563	0.807
	pNN50	FS	5.38 ± 3.88	0.231	0.187	7.84 ± 3.49	0.135	0.130	2.68 ± 4.13	0.563	0.807
Frequency domain
	HF	N-FS	−485.55 ± 288.15	0.007^*	0.006^*	−262.27 ± 307.57	0.019^*	0.018^*	−147.25 ± 340.37	0.840	0.394
	HF	FS	572.39 ± 262.72	0.007^*	0.006^*	669.12 ± 192.31	0.019^*	0.018^*	244.95 ± 248.54	0.840	0.394
	LF/HF ratio	N-FS	0.32 ± 0.24	0.035^*	0.030^*	0.28 ± 0.18	0.037^*	0.108	0.06 ± 0.29	0.904	0.918
	LF/HF ratio	FS	−0.35 ± 0.19	0.035^*	0.030^*	−0.15 ± 0.14	0.037^*	0.108	0.09 ± 0.26	0.904	0.918
	LF nu	N-FS	0.07 ± 0.05	0.069	0.056	0.06 ± 0.04	0.026^*	0.048^*	0.00 ± 0.06	0.510	0.771
	LF nu	FS	−0.06 ± 0.05	0.069	0.056	−0.06 ± 0.03	0.026^*	0.048^*	−0.02 ± 0.05	0.510	0.771
	HF nu	N-FS	−0.07 ± 0.05	0.069	0.056	−0.06 ± 0.04	0.026^*	0.048^*	0.00 ± 0.06	0.510	0.771
	HF nu	FS	0.06 ± 0.05	0.069	0.056	0.06 ± 0.03	0.026^*	0.048^*	0.02 ± 0.05	0.510	0.771
Nonlinear domain
	SD1	N-FS	−2.79 ± 3.54	0.104	0.060	−1.85 ± 3.99	0.065	0.043^*	1.74 ± 4.19	0.798	0.842
	SD1	FS	6.16 ± 3.20	0.104	0.060	9.22 ± 2.54	0.065	0.043^*	2.97 ± 3.26	0.798	0.842
	SampEn	N-FS	−0.04 ± 0.04	0.166	0.143	0.05 ± 0.04	0.619	0.776	0.03 ± 0.06	0.798	0.935
	SampEn	FS	0.10 ± 0.07	0.166	0.143	0.03 ± 0.05	0.619	0.776	0.04 ± 0.06	0.798	0.935
	DFA1	N-FS	0.11 ± 0.07	0.042^*	0.029^*	0.05 ± 0.05	0.069	0.105	0.00 ± 0.09	0.638	0.684
	DFA1	FS	−0.10 ± 0.06	0.042^*	0.029^*	−0.08 ± 0.05	0.069	0.105	−0.03 ± 0.07	0.638	0.684

Values are means ± SEM. P-values are calculated by Wilcoxon's signed-rank test.

rMSSD, square root of the mean squared differences between successive RR intervals; pNN50, NN50 (number of successive RR interval pairs that differ more than 50 ms) divided by the total number of RR interval; N-FS, non-feeding session; FS, feeding session; HF, high frequency (0.15–0.4 Hz); LF/HF ratio, ratio between low frequency (0.04–0.15 Hz) and high frequency; LF nu, low frequency normalized unit; HF nu, high frequency normalized unit; SD1, SD of the instantaneous beat-to-beat variability of data; SampEn, smaple entropy; DFA1, detrended fluctuation analysis index alpha1 short term fractal scaling exponent; SEM, standard error of mean.

^*P < 0.05.