Table 2 Association between quality of sleep and shift work, and other factors

Length of night–shift Cycle

 Group A (6 weeks)

1

1

 Group B (4 weeks)

1.456

1.171–1.811

1.419

1.134–1.777

 Group C (12 days)

2.348

1.852–2.977

2.238

1.737–2.882

Age

 20–29

1

1

 30–39

0.834

0.665–1.046

0.883

0.670–1.163

Obesity (BMI)

 18.5–24.9

1

1

  < 18.5

1.000

0.787–1.270

1.059

0.844–1.329

  ≥ 25.0

1.119

0.891–1.403

1.072

0.865–1.328

Smoking

 No

1

1

 Current

1.990

1.482–2.670

1.415

1.053–1.899

Alcohol consumption

 No

1

1

 Mild

1.193

0.987–1.443

1.133

0.948–1.354

 Moderate

1.611

1.314–1.976

1.418

1.170–1.720

Regular Exercise

  < 3 times per weeks

1

1

  ≥ 3 times per weeks

0.962

0.818–1.133

0.936

0.803–1.092

Job tenure

  < 5 years

1

1

 5–9 years

0.904

0.747–1.093

0.552

0.340–0.896

  ≥ 10 years

0.798

0.653–0.976

0.474

0.275–0.816

Job tenure (Shift work)

  < 5 years

1

1

 5–9 years

0.937

0.781–1.125

1.557

0.964–2.515

  ≥ 10 years

0.848

0.682–1.053

1.906

1.102–3.296

Sleep during working

 Impossible

1

1

 Possible

1.015

0.810–1.273

1.199

0.951–1.511