Table 3.

Univariate Analysis.

Variables	No sleep problems (n = 1,978), mean (SD)	Sleep problems (n = 472), mean (SD)	p-Value	ES
Depressive mood	2.55 (1.09)	3.68 (0.98)	<0.001	1.04
Fatigue	2.94 (0.93)	3.79 (0.89)	<0.001	0.92
Poor gastrointestinal condition	1.53 (0.75)	2.18 (0.99)	<0.001	0.82
Constipation or diarrhea	1.64 (0.83)	2.26 (0.99)	<0.001	0.72
Job and life satisfaction	3.39 (0.84)	2.81 (0.83)	<0.001	0.69
Poor appetite	1.29 (0.56)	1.71 (0.82)	<0.001	0.68
Low back pain	1.87 (0.95)	2.44 (1.06)	<0.001	0.59
Interpersonal stress at work	2.78 (0.90)	3.31 (0.96)	<0.001	0.58
Job control	3.36 (0.86)	2.93 (0.90)	<0.001	0.496
Supervisor support	3.39 (1.00)	2.93 (1.06)	<0.001	0.46
Family and friend support	3.65 (1.31)	3.11 (1.48)	<0.001	0.40
Psychological job demands (quantitative)	3.24 (0.90)	3.54 (0.93)	<0.001	0.34
Perceived physical burden	3.39 (0.96)	3.61 (1.06)	<0.001	0.22

Notes: Poor gastrointestinal condition, constipation or diarrhea, poor appetite, and low back pain were assessed as single items scored on a four-point scale (1-4); the remaining variables were Brief Job Stress Questionnaire domain scores calculated from multiple items. Differences were considered statistically significant at p < 0.05. p- Values were calculated using Student’s t test, and ESs are presented as Cohen’s d.

ES: effect size; SD: standard deviation.