Table 3 Comparison of time series data among the OD (off-duty), 2NS (two night shifts) and 4NS (four night shifts) groups

Sleep related hormone

Prolactin (ng/ml)

Off-duty

9.7 ± 3.0

8.5 ± 3.5

8.6 ± 2.9

9.8 ± 3.7

6.31

0.003^a

Two night shifts

11.8 ± 6.0

12.5 ± 7.0

13.4 ± 7.0

14.9 ± 6.6

Four night shifts

8.1 ± 2.2

8.2 ± 3.0

9.6 ± 2.9

11.1 ± 3.5

Growth hormone (ng/ml)

Off-duty

1.3 ± 4.0

1.3 ± 2.0

0.5 ± 1.3

1.2 ± 2.6

0.36

0.697

Two night shifts

1.4 ± 3.0

1.0 ± 1.6

0.6 ± 1.0

1.9 ± 2.4

Four night shifts

1.1 ± 0.8

0.9 ± 0.5

0.6 ± 0.9

1.1 ± 1.1

Thyrotropin (mIU/L)

Off-duty

1.0 ± 0.6

1.0 ± 0.6

1.0 ± 0.6

1.1 ± 0.6

6.64

0.003^b

Two night shifts

1.3 ± 0.7

1.5 ± 0.7

1.9 ± 0.9

2.0 ± 0.7

Four night shifts

1.0 ± 0.4

1.4 ± 0.5

1.7 ± 0.7

2.1 ± 0.8

Cortisol (μg/dl)

Off-duty

5.7 ± 3.4

6.0 ± 2.8

4.9 ± 2.8

5.2 ± 2.9

0.12

0.884

Two night shifts

5.5 ± 2.2

5.9 ± 2.3

4.5 ± 3.0

4.4 ± 2.1

Four night shifts

5.4 ± 3.1

5.3 ± 3.0

5.2 ± 2.5

5.1 ± 2.5