Table 1 General characteristics of the study subjects
From: Comparison of sleep quality based on direction of shift rotation in electronics workers
| Â | Total | Forward rotation | Backward rotation | P value* |
|---|---|---|---|---|
Number of participants | 4750 | 4238 (89.2) | 512 (10.8) | Â |
Age, years | 27.5 ± 4.4 | 27.5 ± 4.5 | 27.9 ± 3.6 | 0.001 |
Sex | Â | Â | Â | <0.001 |
 Male | 1749 | 1359 (77.7) | 390 (22.3) |  |
 Female | 3001 | 2879 (95.9) | 122 (4.1) |  |
BMI, kg/m2 | 23.0 ± 4.0 | 22.9 ± 4.1 | 23.6 ± 3.5 | <0.001 |
Duration of shift work | Â | Â | Â | <0.001 |
 <5 years | 1870 | 1517 (81.1) | 353 (18.9) |  |
 5–9 years | 1738 | 1635 (94.1) | 103 (5.9) |  |
 ≥10 years | 1142 | 1086 (95.1) | 56 (4.9) |  |
Weekly working hours | Â | Â | Â | <0.001 |
 <41 h | 1013 | 933 (92.1) | 80 (7.9) |  |
 41–51 h | 3115 | 2835 (91.0) | 280 (9.0) |  |
 52–59 h | 516 | 398 (77.1) | 118 (22.9) |  |
 ≥60 h | 106 | 72 (67.9) | 34 (10.8) |  |
Smoking status | Â | Â | Â | <0.001 |
 Non-smoker | 3638 | 3308 (90.9) | 330 (9.1) |  |
 Ex-smoker | 1081 | 903 (83.5) | 178 (16.5) |  |
 Current smoker | 31 | 27 (87.1) | 4 (12.9) |  |
Alcohol consumption | Â | Â | Â | <0.001 |
 Non-drinker | 1896 | 1749 (92.2) | 147 (7.8) |  |
 Regular drinker | 2450 | 2120 (86.5) | 330 (13.5) |  |
 Heavy drinker | 404 | 369 (91.3) | 35 (8.7) |  |
Physical activity | Â | Â | Â | <0.001 |
 Sufficient exercise | 1544 | 1339 (86.7) | 205 (13.3) |  |
 Insufficient exercise | 3206 | 2899 (90.4) | 307 (9.6) |  |
Sleep duration, hours | 7.0 ± 1.6 | 7.0 ± 1.6 | 6.9 ± 1.4 | 0.011 |
PSQI score, points | 4.4 ± 2.7 | 4.3 ± 2.7 | 4.9 ± 2.6 | <0.001 |