Table 4.

PSQI scores according to the PHQ-9.

PSQI component	No depression		Probable depression		t	p
	Mean	SD	Mean	SD
Subjective sleep quality	0.55	0.63	1.09	0.76	−6.077	<0.001
Sleep latency	0.82	0.99	1.33	1.19	−3.721	<0.001
Sleep duration	0.40	0.86	0.88	1.17	−3.857	<0.001
Habitual sleep efficiency	0.30	0.66	0.42	0.81	−1.365	0.173
Sleep disturbance	0.67	0.58	1.00	0.61	−4.163	<0.001
Use of sleep medication	0.03	0.22	0.08	0.40	−1.431	0.153
Daytime dysfunction	0.73	0.94	1.62	1.17	−6.647	<0.001
Total score of the PSQI	3.50	3.05	6.42	3.90	−6.741	<0.001

PHQ-9, 9-item Patient Health Questionnaire Depression Scale; PSQI, Pittsburgh Sleep Quality Index.