Table 5. Correlation analysis between electrocardiogram metrics and PVT performance.

Features	Mean reaction time		Median reaction time		Fastest 10% reaction time		Slowest 10% reaction time
	r	p	r	p	r	p	r	p
Mean RR	0.054	0.190	0.054	0.190	0.081	0.048*	-0.003	0.936
SDNN	-0.068	0.096	-0.177	<.0001***	-0.237	<.0001***	-0.041	0.312
Mean HR	-0.197	<.0001***	-0.068	0.096	-0.099	0.016*	0.001	0.986
SDHR	-0.217	<.0001***	-0.197	<.0001***	-0.299	<.0001***	-0.020	0.620
HR Max-min	-0.155	<.0001***	-0.133	0.001**	-0.245	<.0001***	0.025	0.540
RMSSD	-0.139	<.0001***	-0.217	<.0001***	-0.275	<.0001***	-0.061	0.137
NN50	-0.120	0.003**	-0.155	<.0001***	-0.164	<.0001***	-0.064	0.120
pNN50	-0.228	<.0001***	-0.139	<.0001***	-0.137	0.001**	-0.067	0.100
RR tri index	-0.133	0.001**	-0.120	0.003**	-0.122	0.003**	-0.076	0.064
TINN	0.054	0.190	-0.228	<.0001***	-0.296	<.0001***	-0.031	0.449
Total power	0.025	0.541	-0.160	<.0001***	-0.208	<.0001***	-0.034	0.399
peakVLF	-0.108	0.008**	0.025	0.541	-0.002	0.960	0.004	0.924
peakLF	-0.061	0.133	-0.108	0.008**	0.058	0.156	-0.168	<.0001***
peakHF	0.036	0.384	-0.061	0.133	-0.031	0.451	-0.008	0.848
aVLF	-0.109	0.008**	0.036	0.384	-0.124	0.002**	0.130	0.001**
aLF	-0.198	<.0001***	-0.109	0.008**	-0.137	0.001**	-0.022	0.590
aHF	0.068	0.094	-0.198	<.0001***	-0.237	<.0001***	-0.064	0.116
VLF(log)	-0.111	0.007**	0.068	0.094	-0.121	0.003**	0.174	<.0001***
LF(log)	-0.194	<.0001***	-0.111	0.007**	-0.111	0.006**	-0.030	0.459
HF(log)	0.252	<.0001***	-0.194	<.0001***	-0.182	<.0001***	-0.071	0.082*
VLF	0.082	0.045*	0.252	<.0001***	0.057	0.160	0.234	<.0001***
LF	-0.170	<.0001***	0.082	0.045*	0.111	0.006**	0.007	0.867
HF	0.146	<.0001***	-0.170	<.0001***	-0.125	0.002**	-0.093	0.022*
LF norm	-0.145	<.0001***	0.146	<.0001***	0.121	0.003**	0.070	0.088
HF norm	-0.160	<.0001***	-0.145	<.0001***	-0.120	0.003**	-0.070	0.086
LF/HF	0.100	0.014*	0.100	0.014*	0.115	0.005**	0.027	0.515
DFA alpha 1	0.172	<.0001***	0.172	<.0001***	0.169	<.0001***	0.052	0.202
DFA alpha 2	0.164	<.0001***	0.164	<.0001***	-0.046	0.256	0.227	<.0001***
SD1	-0.234	<.0001***	-0.234	<.0001***	-0.280	<.0001***	-0.069	0.092
SD2	-0.141	<.0001***	-0.141	<.0001***	-0.195	<.0001***	-0.028	0.500
SD2/SD1	0.147	<.001***	0.148	<.0001***	0.136	0.001**	0.061	0.137
ApEn	0.122	0.003**	0.122	0.003**	0.184	<.0001***	-0.007	0.862
SampEn	0.097	0.017*	0.097	0.017*	0.198	<.0001***	-0.039	0.346

* P< 0.05,** P < 0.01,*** P < 0.001.