Table 5.

Descriptive statistics and correlations for primary PSQI indices of sleep quality, BDI-II score, and HRV during awake period.

Variable	M ±SD	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
PSQI component scores
1. Subjective sleep quality	1.04 ± 0.72	1
2. Sleep latency	0.85 ± 0.87	0.554**	1
3. Sleep duration	0.79 ± 0.50	0.269*	0.158	1
4. Habitual sleep efficiency	0.10 ± 0.34	0.157	0.091	0.121	1
5. Sleep disturbance	0.96 ± 0.49	0.374**	0.339**	0.173	0.137	1
6. Use of sleeping medication	0.14 ± 0.51	0.273*	0.341**	0.300*	0.095	0.230	1
7. Daytime dysfunction	1.42 ± 0.95	0.511**	0.398**	0.204	0.187	0.330**	0.389**	1
8. PSQI global scores	5.29 ± 2.84	0.769**	0.763**	0.396**	0.259*	0.535**	0.454**	0.774**	1
9. BDI-II score	8.26 ± 8.61	0.555**	0.383**	0.191	0.147	0.372**	0.288*	0.663**	0.617**	1
10. SDNN	123.11 ± 29.71	−0.046	−0.118	−0.106	0.032	−0.285*	−0.099	0.018	−0.127	0.040	1
11. RMSSD	36.52 ± 13.08	−0.022	−0.016	−0.002	−0.039	−0.112	−0.112	−0.011	−0.035	0.040	0.667**	1
12. pNN50	14.50 ± 9.44	−0.059	−0.024	−0.008	−0.042	−0.128	−0.100	−0.021	−0.057	0.027	0.645**	0.982**	1
13. LF	971.36 ± 392.77	−0.093	−0.086	−0.082	0.085	−0.239*	−0.146	−0.026	−0.136	−0.021	0.608**	0.685**	0.665**	1
14. HF	551.85 ± 449.87	−0.029	0.101	−0.017	0.030	−0.043	−0.128	−0.001	0.041	0.053	0.573**	0.930**	0.906**	0.680**	1
15. LF/HF	2.39 ± 1.35	−0.037	−0.202	−0.034	0.106	−0.078	0.088	0.064	−0.119	−0.042	−0.308**	−0.694**	−0.670**	−0.114	−0.757**	1

^*p < 0.05,

^**p < 0.01.