Table 2.
Comparison of time series data among the OD (off-duty), 2NS (two night shifts) and 4NS (four night shifts) groups
| Variables (mean ± SD) | Group ( n = 23, 20, 16) | Time 1 | Time 2 | Time 3 | Time 4 | F(2,56) | P- value |
|---|---|---|---|---|---|---|---|
| Wisconsin Card Sorting Test | |||||||
| Number of categories | Off-duty | 7.6 ± 1.9 | 8.0 ± 1.5 | 8.5 ± 1.3 | 8.8 ± 1.2 | 0.08 | 0.926 |
| Two night shifts | 7.9 ± 2.3 | 8.4 ± 2.2 | 8.2 ± 2.3 | 8.1 ± 2.2 | |||
| Four night shifts | 8.4 ± 1.4 | 8.3 ± 1.2 | 8.3 ± 1.3 | 8.3 ± 1.1 | |||
| % of conceptual level responses | Off-duty | 73.7 ± 14.5 | 79.4 ± 8.9 | 81.7 ± 8.2 | 84.7 ± 5.9 | 0.81 | 0.449 |
| Two night shifts | 76.7 ± 15.7 | 79.4 ± 13.1 | 78.8 ± 15.0 | 77.6 ± 14.8 | |||
| Four night shifts | 81.2 ± 7.1 | 82.0 ± 6.7 | 81.6 ± 6.0 | 83.8 ± 3.1 | |||
| Failure to maintain set | Off-duty | 1.2 ± 0.9 | 1.8 ± 1.4 | 1.4 ± 1.3 | 1.4 ± 1.4 | 2.47 | 0.094 |
| Two night shifts | 1.2 ± 0.8 | 1.6 ± 1.2 | 1.2 ± 1.1 | 1.3 ± 1.6 | |||
| Four night shifts | 1.8 ± 1.3 | 1.8 ± 1.3 | 1.7 ± 1.3 | 2.3 ± 1.3 | |||
| Digit Symbol Substitution Test | |||||||
| Scoring scale | Off-duty | 14.7 ± 1.6 | 15.2 ± 1.9 | 15.6 ± 1.9 | 16.5 ± 2.1 | 4.72 | 0.013a |
| Two night shifts | 13.3 ± 2.8 | 14.0 ± 2.7 | 14.4 ± 2.8 | 14.4 ± 2.9 | |||
| Four night shifts | 12.1 ± 3.5 | 13.4 ± 2.9 | 14.0 ± 2.8 | 14.2 ± 2.0 | |||
| Symbol Searching Test | |||||||
| Scoring scale | Off-duty | 14.4 ± 1.1 | 15.5 ± 2.6 | 15.6 ± 2.0 | 16.7 ± 1.8 | 6.28 | 0.003a |
| Two night shifts | 13.3 ± 3.2 | 13.8 ± 2.4 | 14.4 ± 3.1 | 14.9 ± 2.8 | |||
| Four night shifts | 11.7 ± 4.1 | 12.8 ± 3.6 | 12.7 ± 3.5 | 14.1 ± 2.8 | |||
| Information process index | Off-duty | 126.0 ± 7.7 | 130.3 ± 10.7 | 131.5 ± 9.2 | 137.7 ± 9.0 | 7.21 | 0.002a |
| Two night shifts | 118.0 ± 14.6 | 121.6 ± 13.2 | 124.6 ± 14.7 | 126.0 ± 13.7 | |||
| Four night shifts | 110.9 ± 18.1 | 117.1 ± 17.2 | 116.1 ± 18.8 | 123.9 ± 12.6 |
Scheffé’s s post-hoc test: aOD group > 2NS group, OD group > 4NS group.