Table 7. Summary of heart rate variability according to CSHQ.

Characteristics	Total (n = 92)	Low CSHQ (n = 28)	High CSHQ (n = 64)	F	P value
HR	74.84 ± 7.33	74.98 ± 8.57	74.78 ± 6.80	0.028	0.866
RMSSD	63.24 ± 31.21	71.95 ± 42.72	59.43 ± 24.02	3.367	0.070
NN50	114.97 ± 57.48	115.79 ± 65.44	114.61 ± 54.18	0.000	0.999
pNN50	34.01 ± 18.81	35.10 ± 22.42	33.54 ± 17.17	0.079	0.779
nLF	51.90 ± 13.51	51.16 ± 16.30	52.22 ± 12.23	0.050	0.823
nHF	48.10 ± 13.51	48.84 ± 16.30	47.78 ± 12.23	0.050	0.823
RATIO	1.41 ± 0.79	1.42 ± 0.86	1.41 ± 0.76	0.111	0.740
LF	1,849.78 ± 1,363.30	2,177.99 ± 1,883.33	1,706.18 ± 1,046.75	2.311	0.132
HF	1,830.51 ± 1,916.07	2,468.84 ± 2,899.83	1,551.24 ± 1,199.51	4.855	0.030*
TP	9,094.24 ± 6,811.09	10,602.22 ± 9,482.89	8,434.50 ± 5,197.78	1.924	0.169

Data are shown as mean ± standard deviation.

CSHQ = children's sleep habits questionnaire, HR = heart rate, RMSSD = root mean square of successive difference of successive normal-to-normal, NN50 = difference between adjacent normal-to-normal intervals of 50 ms or more, pNN50 = NN50/total number of all normal-to-normal, nLF = low-frequency power in normalized units, nHF = high-frequency power in normalized units, RATIO = LF/HF ratio, LF = power in low-frequency range, HF = power in high-frequency range, TP = total power.

^*P < 0.05.