Table 4.
Geometric means for urinary melatonin circadian rhythm parameters across chronotype categories, stratified by shift work1,2
| Day-shift workers | Rotating-shift workers | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Day/off shifts | Day/off shifts | Night shifts | |||||||
| Morning type | Intermediate type | Evening type | Morning type | Intermediate type | Evening type | Morning type | Intermediate type | Evening type | |
|
Time of Peak Onset (in
hours) Geometric mean (95% CI) | |||||||||
| Model 13 | 4.02 (3.36–4.82) |
4.39 (3.97–4.86) |
4.14 (3.22–5.31) |
2.95a,b (2.36–3.69) |
4.99a (4.37–5.71) |
5.82b (4.57–7.41) |
3.43a,b (2.59–4.54) |
6.26a (5.28–7.43) |
6.21b (4.39–8.76) |
| Model 24 | 4.96 (3.58–6.86) |
5.48 (4.16–7.22) |
5.60 (3.79–8.27) |
3.48a (2.62–4.62) |
6.01a (4.88–7.42) |
5.22 (3.85–7.09) |
3.56a (2.39–5.30) |
6.23a (4.69–8.26) |
5.51 (3.57–8.50) |
|
Mean Levels (in
ng/mg-creatinine/hour) Geometric mean (95% CI) | |||||||||
| Model 13 | 21.29b (17.43–26.01) |
19.06c (17.05–21.31) |
13.22b,c (10.03–17.43) |
21.54 (16.34–28.39) |
19.23 (16.28–22.71) |
15.27 (11.33–20.59) |
14.03 (11.26–17.49) |
16.30 (14.25–18.64) |
17.37 (13.25–22.78) |
| Model 24 | 18.53b (13.32–25.78) |
14.62c (11.06–19.33) |
9.76b,c (6.58–14.49) |
21.57 (15.27–30.48) |
17.61 (13.64–22.73) |
17.58 (12.12–25.48) |
12.03 (8.81–16.45) |
14.57 (11.67–18.20) |
16.43 (11.68–23.12) |
|
Peak Size (in
ng/mg-creatinine) Geometric mean (95% CI) | |||||||||
| Model 13 | 19.30b (14.63–25.46) |
13.98 (11.98–16.32) |
9.22b (6.29–13.52) |
19.78 (13.89–28.16) |
15.12 (12.23–18.71) |
11.87 (8.11–17.40) |
9.14 (6.84–12.21) |
11.84 (9.93–14.13) |
14.85 (10.39–21.21) |
| Model 24 | 14.42b (9.13–22.80) |
9.96 (6.77–14.67) |
6.39b (3.69–11.05) |
18.25 (11.57–28.81) |
12.92 (9.22–18.10) |
12.87 (7.88–21.02) |
7.42b (4.96–11.09) |
9.81 (7.37–13.07) |
17.15b (11.04–26.64) |
CI=confidence interval
1
Bonferroni correction was applied to address multiple comparisons.
2
Statistically significant differences for group comparisons are indicated as follows:
a
for morning types versus intermediate types,
b
for morning types versus evening types,
c
for intermediate types versus evening types.
3
Model 1 is adjusted for age only.