Table 6.

The internal consistency and test-retest reliability of the PSQI.

PSQI Subscales	Cronbach’s α if Subscale Deleted	Corrected Subscale—Total Correlation	Test-Retest Reliability
Self-reported sleep quality	0.675	0.685	0.731
Sleep latency	0.700	0.527	0.753
Sleep duration	0.723	0.431	0.802
Sleep efficiency	0.739	0.372	0.766
Sleep disturbance	0.710	0.525	0.813
Sleep medicine use	0.712	0.478	0.795
Daytime dysfunction	0.750	0.305	0.709

PSQI = Pittsburgh Sleep Quality Index.