Table 3.
Cross-shift examination concerning sleep characteristics
| Occupational groups | ||||
| Day workers (n=75) | Watchkeepers (n=123) | Crude OR* (95% CI) | Adjusted OR† (95% CI) | |
| Time periods in the context of the current pupillometric examination, mean hours (SD) | ||||
| Sleep period before‡ | 5.8 (1.1) | 5.5 (1.0) | 0.85 (0.78 to 0.92) | 0.88 (0.80 to 0.95) |
| Working hours examined | 9.5 (1.5) | 4.9 (1.6) | 0.56 (0.43 to 0.88) | 0.57 (0.46 to 0.92) |
| Subjective stress level during examined shift, n (SD) | ||||
| Physical§ | 48 (64.0%) | 78 (63.4%) | 0.96 (0.52 to 1.79) | 0.51 (0.24 to 1.08) |
| Mental¶ | 41 (54.7%) | 94 (76.4%) | 2.35 (1.24 to 4.44) | 2.18 (1.08 to 4.40) |
| Sleep efficiency‡ | ||||
| Mean (%) | 72.7% (11.8%) | 67.9% (12.2%) | 0.48 (0.26 to 0.88) | 0.48 (0.25 to 0.91) |
| SSS**, mean (SD) | ||||
| Cross-shift† | 2.6 (1.4) | 3.1 (1.7) | 0.73 (0.48 to 1.10) | 0.84 (0.55 to 1.29) |
| Time depending | ||||
| Before the shift | 2.5 (1.4) | 2.6 (1.5) | 1.07 (0.59 to 1.95) | 0.91 (0.49 to 7.70) |
| After the shift | 2.8 (1.4) | 3.5 (1.9) | 1.81 (1.01 to 3.25) | 1.25 (0.66 to 2.37) |
| rPUI, mean (SD) | ||||
| Cross-shift†† | 1.14 (0.66) | 1.18 (0.65) | 0.92 (0.61 to 1.40) | 1.05 (0.70 to 1.61) |
| Time depending | ||||
| Before the shift | 1.14 (0.67) | 1.12 (0.62) | 0.96 (0.52 to 1.74) | 0.86 (0.46 to 1.61) |
| After the shift | 1.13 (0.66) | 1.23 (0.65) | 1.55 (0.85 to 2.84) | 1.31 (0.70 to 2.46) |
| Level (n=396) of sleepiness on duty†† n (%) | ||||
| None‡‡ | 78 (52.0%) | 120 (48.8%) | 0.789 | |
| Particular attention required§§ | 39 (26.0%) | 71 (28.9%) | ||
| Unfit for duty¶¶ | 33 (22.0%) | 55 (22.3%) | ||
Significant findings are in bold.
*The crude OR bases on the median of parameters and includes differences between occupational groups and the examination time of day.
†Adjusted for age, rank (officer vs rating) and duration of stay on board at the time of examination.
‡According to measurements with the armband monitor, related to an average 24-hour period.
§‘Have you experienced physical stress during the examined shift?’
¶‘Have you experienced mental stress during the examined shift?’
**SSS from 1 (‘feel active and vital’) up to 7 (‘almost dreaming/falling asleep’).
††All values exploited (before and after the shift).
‡‡rPUI<1.02.
§§rPUI ≥1.02 and <1.53.
¶¶rPUI≥1.53.
rPUI, pupillary unrest index; SSS, subjective sleepiness assessment.