Table 2. Comparison of unit characteristics, sleep and fatigue: Day vs Night shift.
| Day shift (n = 47) | Night shift (n = 60) | p-value* | |
|---|---|---|---|
| Median (IQR, R) | Median (IQR, R) | ||
| Unit characteristics | |||
| Bed occupancy | 40 (21–46;17–52) | 23 (20–45;17–52) | 0.104 |
| New admissions | 2 (1–3;0–5) | 1 (0–2;0–4) | 0.157 |
| Emergency call | 0 (0–1;0–2) | 0 (0–1;0–1) | 0.914 |
| Mean (95% CI) | Mean (95% CI) | p-value | |
| Sleep characteristics | |||
| Total sleep quality before shift (rated 1–5) | 3.2 (2.9–3.5) | 2.9 (2.5–3.2) | 0.295 |
| Sleep quality before first shift (hrs) | 3.0 (2.8–3.2) | 3.0 (2.6–3.5) | 0.848 |
| Sleep quality before subsequent shifts (2–4 consecutive shifts) | 3.4 (2.7–4.1) | 2.8 (2.3–3.3) | 0.147 |
| Total sleep before shift (hrs) | 7.6 (7.2–8.1) Range: 6–11 | 7.1 (6.2–7.9) Range: 2–15 | 0.019 |
| Total sleep before first shift (hrs) | 7.8 (7.1–8.6) Range: 6–11 | 8.6 (7.1–10.1) Range: 4–15 | 0.357 |
| Total sleep before subsequent shifts (2–4 consecutive shifts) (hrs) | 7.4 (6.9–7.9) Range: 6–9 | 6.2 (5.1–7.2) Range: 2–9 | 0.034 |
| End of shift PVT measurements† | |||
| RTM (ms) | 308.6 (294.1–323.9) | 333.9 (310.7–358.8) | 0.007 |
| RTCV (ms) | 29.2 (24.8–34.4) | 34.5 (29.5–40.3) | 0.046 |
| Lapses (number of) | 4.1 (2.4–5.8) | 7.5 (4.2–10.8) | 0.001 |
RTM, mean reaction time; RTCV, relative coefficient of variation; ms, milliseconds; PVT, psychomotor vigilance task; IQR, interquartile range; R, range; CI, confidence interval.
*p-values for sleep and PVT measurements were derived using regression analysis for timing of shift effects using the F distribution.
†All end of shift PVT measurements are adjusted for the response at start of shift and quality of sleep before shift.