Table 3. Comparison of the scores in each sleep component of PSQI between good and poor sleepers in SD group.

	Total SD group (n=53)	Good sleeper (n=12)	Poor sleeper (n=41)	p-value (student’s t-test)
PSQI total score	8.9±3.95	3.2±0.3	10.4±0.6	<0.001
Sleep quality	1.49±0.87	0.7±0.5	1.7±0.8	<0.001
Sleep latency*	1.89±0.93	0.8±0.8	2.2±0.7	<0.001
Sleep duration*	1.68±1.12	0.3±0.5	2.1±0.9	<0.001
Sleep-wake patterns	1.25±1.24	0.1±0.3	1.6±1.2	<0.001
Sleep disturbances	1.17±0.51	0.9±0.3	1.2±0.5	0.009
Use of sleep medications	0.25±0.55	0.0±0.0	0.3±0.7	0.002
Daytime dysfunction	1.04±0.78	0.4±0.5	1.2±0.8	0.001

Values are presented as mean±standard deviation. PSQI: Pittsburgh Sleep Quality Index, SD: sleep disturbance. ^*p<0.05 in analysis of covariance.