Table 5 . Linear regression of predictor variables on sleep quality(N=200) .

Variable	B	SE	Β(standardized coefficients)	p
Age	0.054	0.025	0.153	0.036
Type of referral	2.240	0.649	0.229	0.001
Noncardiac Comorbidity	-3.941	1.317	-0.200	0.003
Educational level	0.765	0.350	0.160	0.030

Note: analyzed by the stepwise method.p<0.05