Table 1. Selected baseline characteristics among Chinese workers in a prospective cohort study stratified by night shift work schedules.
| Variables | Daytime workers | Previous night shift workers | Current night shift workers |
|---|---|---|---|
| N (%) | N (%) | N (%) | |
| No. of participants | 1,677 (43.4) | 437 (11.3) | 1,757 (45.4) |
| Age at interview, years (median/ range) | 30/18-61 | 33/18-59 | 28/18-59* |
| Sex | |||
| Male | 1,605 (95.7) | 431 (98.6) | 1,395 (79.5)* |
| Female | 72 (4.3) | 5 (1.4) | 359 (20.5) |
| Education | |||
| Primary or below | 3 (0.2) | 1 (0.2)* | 5 (0.3)* |
| Junior high school | 34 (2.0) | 46 (10.6) | 367 (21.1) |
| Senior high school | 221 (13.2) | 313 (72.1) | 482 (27.7) |
| College or above | 1,410 (84.5) | 74 (17.1) | 885 (50.9) |
| Marital status | |||
| Single | 527 (31.5) | 113 (26.0) | 806 (46.1)* |
| Married | 1,124 (67.3) | 317 (72.9) | 930 (53.2) |
| Divorced | 20 (1.2) | 5 (1.1) | 12 (0.7) |
| Smoking status | |||
| Non-smoker | 1,182 (71.0) | 218 (50.6) | 1,340 (77.2)* |
| Current smoker | 390 (23.4) | 184 (42.7) | 362 (20.9) |
| Former smoker | 93 (5.6) | 29 (6.7) | 34 (2.0) |
| Alcohol drinking | |||
| Non-drinker | 1,244 (74.7) | 230 (52.8) | 1,381 (79.8)* |
| Current drinker | 405 (24.3) | 200 (45.9) | 340 (19.6) |
| Former drinker | 16 (1.0) | 6 (1.4) | 10 (0.6) |
| Leisure-time physical activity | |||
| ≤1 time/week | 559 (33.3) | 181 (41.4) | 754 (42.9)* |
| >1 time/week | 1,118 (66.7) | 256 (58.6) | 1,003 (57.1) |
| Food consumption (fruits) | |||
| Infrequent | 403 (24.0) | 63 (14.4) | 380 (21.6) * |
| Frequent | 1274 (76.0) | 374 (85.6) | 1377 (78.4) |
| Food consumption (vegetables) | |||
| Infrequent | 1129 (67.3) | 275 (62.9) | 934 (53.2) * |
| Frequent | 548 (32.7) | 162 (37.1) | 823 (46.8) |
| Sleep duration | |||
| 6–8 hours per day | 1,074 (72.6) | 321 (77.9) | 868 (58.0)* |
| ≥8 hours per day | 43 (2.9) | 17 (4.1) | 34 (2.3) |
| <6 hours per day | 363 (24.5) | 74 (18.0) | 595 (39.7) |
| Sleep quality | |||
| Good | 730 (44.1) | 122 (28.4) | 572 (33.7)* |
| Fair | 836 (50.5) | 246 (57.2) | 991 (58.4) |
| Bad | 84 (5.1) | 56 (13.0) | 127 (7.5) |
| Extremely bad | 6 (0.4) | 6 (1.4) | 7 (0.4) |
| Working hours | |||
| ≤40 hours/week | 1,191 (71.0) | 418 (95.7) | 768 (43.7)* |
| >40 hours/week | 486 (29.0) | 19 (4.3) | 989 (56.3) |
| Mental stress | |||
| Low level | 1,325 (79.0) | 304 (69.6) | 1394 (79.3) |
| Middle level | 323 (19.3) | 116 (26.5) | 326 (18.6) |
| High level | 29 (1.7) | 17 (3.9) | 37 (2.1) |
| Obese status a | |||
| Non-obesity | 1,142 (68.1) | 267 (61.1) | 1,340 (76.3)* |
| Overweight | 496 (29.6) | 157 (35.9) | 386 (22.0) |
| Obesity | 39 (2.3) | 13 (3.0) | 31 (1.8) |
| Abdominal obesity | 823 (49.1) | 202 (46.2) | 648 (36.9)* |
a Non-obesity: body mass index (BMI) <25 kg/m2; overweight, BMI 25–30 kg/m2; obesity: BMI≥30 kg/m2; abdominal obesity: waist circumference >85 cm for men or >80 cm for women
* Comparing to daytime workers, p <0.05.