Table 1.
Characteristics of the study population stratified for night-shift and non-shift workers.
| Night-shift workers (n = 254) % (n) | Non-shift workers (n = 57) % (n) | |
|---|---|---|
| Age (in years, mean (SD)) | 42.1* (11.9) | 47.4* (9.9) |
| Gender (% female) | 88.6 (225) | 86.0 (49) |
| CMV status (% positive) | 38.2 (97) | 38.6 (22) |
| Occupation (% nurse) | 83.1* (211) | 35.1* (20) |
| Educational level (% high) | 53.9* (137) | 71.9* (41) |
| Marital status (% married/living together) | 76.0 (193) | 77.2 (44) |
| General health (% very good/excellent) | 50.4 (128) | 54.4 (31) |
| Smoker (% yes) | 9.4 (24) | 5.3 (3) |
| Recent infection (% yes) | 11.0 (28) | 10.5 (6) |
| Influenza vaccination (% yes) | 14.6 (37) | 24.6 (14) |
| Chronotype (%) | ||
| Morning type | 34.3* (87) | 57.9* (33) |
| Evening type | 42.1* (107) | 22.8* (13) |
| Intermediate type | 23.6 (60) | 19.3 (11) |
| Frequency of night shifts (%) | — | |
| 1–2 night shifts/month | 17.3 (44) | |
| 3–4 night shifts/month | 47.2 (120) | |
| ≥5 night shifts/month | 35.4 (90) | |
| Years of night-shift work (%) | — | |
| <10 years | 33.1 (84) | |
| 10–19 years | 24.4 (62) | |
| ≥20 years | 42.5 (108) | |
| Night shift in past three days (% yes) | 22.8 (58) | — |
*Statistically significant difference (p < 0.05) between night-shift workers and non-shift workers tested using the independent-samples t-test and chi-square test.