Table A2.

Contribution of variables to the components in PCA

Variable	Comp1	Comp2	Comp3	Comp4	Comp5	Unexplained
Very or fairly bad sleep quality	0.496	−0.341	0.141	0.784	0.062	0.000
Cannot get to sleep within 30 min	0.509	0.367	−0.294	−0.052	−0.720	0.000
Wakes up mid-night or early morning	0.501	0.324	−0.382	−0.162	0.687	0.000
Takes medicine to help sleep	0.327	0.297	0.865	−0.237	0.046	0.000
Hours of sleep per day	−0.371	0.746	0.031	0.548	0.065	0.000