Table 2.

Factor matrix for the two-factor solution of the Pittsburgh Sleep Quality Index.

PSQI Subscale	Factor 1: perceived sleep quality	Factor 2: perceived sleep efficiency
Subjective sleep quality	0.63	0.23
Sleep latency	0.61	0.25
Sleep duration	0.12	0.78
Habitual sleep efficiency	− 0.04	0.84
Sleep disturbances	0.74	0.05
Sleep medication use	0.60	− 0.23
Daytime dysfunction	0.74	− 0.02
% of total variance	37.73	16.75