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Table 1 General characteristics of the study subjects

From: Comparison of sleep quality based on direction of shift rotation in electronics workers

  Total Forward rotation Backward rotation P value*
Number of participants 4750 4238 (89.2) 512 (10.8)  
Age, years 27.5 ± 4.4 27.5 ± 4.5 27.9 ± 3.6 0.001
Sex     <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     <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     <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     <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     <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     <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
  1. Values are number (%) or mean ± Standard Deviation (SD), unless otherwise indicated
  2. P value* = Chi-square test or Mann-Whitney test