Shortening of the Pittsburgh Sleep Quality Index Survey Using Factor Analysis

Table 4

Rotated factor loading in factor analysis Using Promax rotation.

PSQI and Fruved questions	Factor 1	Factor 2	Factor 3	Factor 4	Factor 5	Factor 6
(Q2) How long has it taken you to fall asleep?	0.034972	0.787579	0.031071
(Q3)-(Q1) Hours in bed?	0.836975
(Q4) Actual sleep hours?	0.846725
(Q5a) Can’t get to sleep within 30 min?	0.002007	0.800826
(Q5b) Wake up in the middle of the night or early?				1.019651
(Q5c) Get up to use the bathroom?
(Q5d) Can’t breathe comfortably?			0.39047
(Q5e) Cough or snore loudly?					1.003774	0.001288
(Q5f) Do you feel too cold?	0.022562		0.252864	0.095624	0.105187	0.123154
(Q5g) Do you feel too hot?	0.090277	0.038497	0.378038	0.124697	0.034749	0.032433
(Q5h) Do you have bad dreams?			0.434513	0.159701
(Q5i) Do you have a pain?			0.575351
(Q5j) Other reasons and how often?
(Q6) Overall sleep quality
(Q7) How often do you use medicine to help you sleep?
(Q8) Do you have trouble staying awake during the day?						0.560634
(Q9) Do you have problem keeping enthusiasm and getting things done?						0.657612

(Q3)–(Q1) represents Q1 value being subtracted from Q3, that is, (Q3 in military time) + (24–Q1 in military time).