Table 1.
Comparison of demographic and clinical characteristics between night-shift workers and daytime workers.
| Characteristics | Daytime Workers (n = 432) | Night-Shift Workers (n = 412) | P |
|---|---|---|---|
| Sex, male | 43 (10.0) | 25 (6.1) | .038 |
| Age, years | 36.39 ± 11.38 | 29.02 ± 6.99 | < .001 |
| Body mass index, kg/m2 | 21.83 ± 2.82 | 21.08 ± 2.79 | < .001 |
| Marital status, married | 212 (49.1) | 91 (22.1) | < .001 |
| Education, college graduates | 346 (80.1) | 390 (94.7) | < .001 |
| Current smoking | 24 (5.6) | 6 (1.5) | .001 |
| Drinking | 206 (47.7) | 259 (62.9) | < .001 |
| Caffeine consumption, cups/day | 1.29 ± .98 | 1.14 ± .85 | .014 |
| Physical activity | 165 (38.2) | 129 (31.3) | .036 |
| Medical comorbidities | 72 (16.7) | 59 (14.3) | .347 |
| PSQI*, score | 6.17 ± .16 | 8.44 ± .16 | < .001 |
| Self-reported poor sleep quality (PSQI > 5) | 209 (48.4) | 325 (78.9) | < .001 |
| ESS*, score | 7.85 ± .16 | 8.48 ± .16 | .007 |
| Excessive daytime sleepiness (ESS > 10) | 80 (18.5) | 124 (30.1) | < .001 |
| MEQ*, score | 46.97 ± .36 | 42.75 ± .37 | < .001 |
| HADS*, score | 10.95 ± .28 | 13.41 ± .29 | < .001 |
| FSS*, score | 29.68 ± .54 | 34.78 ± .55 | < .001 |
| CD-RISC*, score | 64.04 ± .68 | 61.92 ± .70 | .036 |
| QOL-BREF-physical health*, score | 67.59 ± .73 | 61.50 ± .75 | < .001 |
| QOL-BREF-psychological health*, score | 64.53 ± .76 | 61.14 ± .78 | .003 |
| QOL-BREF-social relationship*, score | 65.09 ± .78 | 62.09 ± .80 | .010 |
| QOL-BREF-environmental health*, score | 67.83 ± .70 | 64.33 ± .72 | .001 |
| Actigraphy*,† | |||
| Sleep onset latency, min | 5.70 ± .29 | 5.60 ± .34 | .834 |
| Total sleep time, min | 391.16 ± 3.05 | 399.52 ± 3.58 | .085 |
| Sleep efficiency, % | 85.94 ± .33 | 83.94 ± .39 | < .001 |
| Wake after sleep onset, min | 58.87 ± 1.67 | 70.47 ± 1.97 | < .001 |
Data are presented as mean ± standard deviation for numerical data and number (percentage) for categorized data. *Data are presented as adjusted means ± standard error. Analysis of covariance was performed after controlling for age and sex. †Analysis was performed for 150 night-shift workers and 203 daytime workers. CD-RISC = Connor–Davidson resilience scale, ESS = Epworth Sleepiness Scale, FSS = Fatigue Severity Scale, HADS = Hospital Anxiety and Depression Scale, MEQ = Morningness–Eveningness Questionnaire, PSQI = Pittsburgh Sleep Quality Index, QOL-BREF = Quality of Life Scale Abbreviated Version.