Table 4

Hierarchical regression analysis with sleep-related night shift tolerance total score as the dependent variable (N=575)

Predictor	B	SE B	β	t		R²/ΔR²
Step 1						0.024/0.024**
Age	−0.06	0.027	−0.10	−2.22	*
Gender (male=1, female=2)	−0.37	0.700	−0.02	−0.54
Marital status (partner=1, no partner=2)	1.00	0.479	0.09	2.10	*
Children (yes=1, no=2)	0.14	0.452	0.02	0.32
Step 2						0.029/0.006
Age	−0.08	0.029	−0.13	−2.72	**
Gender (male=1, female=2)	−0.32	0.714	−0.02	−0.45
Marital status (partner=1, no partner=2)	1.01	0.482	0.09	2.09	*
Children (yes=1, no=2)	0.20	0.466	0.02	0.43
Alcohol	−0.08	0.077	−0.05	−1.06
Caffeine (cups of caffeine beverages in a day)	0.13	0.090	0.06	1.39
Smoking (yes=1, no=2)	−0.40	0.759	−0.02	−0.52
Step 3						0.034/0.005
Age	−0.06	0.031	−0.11	−2.07	*
Gender (male=1, female=2)	−0.24	0.721	−0.01	−0.33
Marital status (partner=1, no partner=2)	0.96	0.483	0.09	2.00	*
Children (yes=1, no=2)	0.08	0.474	0.01	0.17
Alcohol	−0.09	0.077	−0.05	−1.19
Caffeine (cups of caffeine beverages in a day)	0.12	0.092	0.06	1.32
Smoking (yes=1, no=2)	−0.35	0.761	−0.02	−0.46
Percentage position	0.12	0.215	0.02	0.55
Number of years worked as a nurse	−0.08	0.056	−0.06	−1.34
Night shifts worked during the last year	0.01	0.009	0.05	1.08
Step 4						0.207/.173***
Age	−0.08	0.029	−0.14	−2.84	**
Gender (male=1, female=2)	−0.23	0.663	−0.01	−0.35
Marital status (partner=1, no partner=2)	0.67	0.443	0.06	1.51
Children (yes=1, no=2)	−0.06	0.435	−0.01	−0.14
Alcohol	−0.11	0.071	−0.06	−1.34
Caffeine (cups of caffeine beverages in a day)	0.06	0.084	0.03	0.74
Smoking (yes=1, no=2)	−0.11	0.703	−0.01	−0.58
Percentage position	0.20	0.196	0.04	1.04
Number of years worked as a nurse	−0.03	0.051	−0.03	−0.58
Night shifts worked during the last year	−0.01	0.008	−0.03	−0.86
Morningness	−0.01	0.067	−0.01	−0.12
Languidity	−0.14	0.063	−0.10	−2.16	*
Flexibility	0.46	0.053	0.37	8.71	***
Hardiness	0.09	0.043	0.09	2.15	*

*p< 0.05, **p < 0.01, ***p< 0.001.
β, Standardised coefficients; B, non-standardised coefficients; SE B, the SE of β.