Table 2 characteristics and baseline variables of the subjects
| Variables | m (SD) |
|---|---|
| age | 31.10 ± 2.60 |
| Shift work experience (year) | 6.30 ± 1.00 |
| Body mass index (BMI) | 24.2 (3.8) |
| Sleep quantity (h) | 7.00 ± 1.12 |
| Sleep quantity | 6.70 ± 3.62 |
| Light (lx) | 530.50 ± 34.20 |