Table 3.
The estimated difference of sleep duration and quality after the last night shift in the 2+2 and 4+4 schedules compared to the second and fourth night shift in the 7+7 schedule. Statistically significant results are shown in bold. N=73 police officers, who performed all three different work schedules in the study. [Diff=difference; SD=standard deviation; PSD=primary sleep duration; TST=total sleep time (including naps)]
| 2+2 a | 4+4 a | |||||
|---|---|---|---|---|---|---|
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| Diff. | SD | P-value | Diff. | SD | P-value | |
| PSD (h:mm) b | 1:01 | 0:13 | <0.001 | 0:51 | 0:10 | <0.001 |
| TST (h:mm) b | 0:53 | 0:14 | <0.001 | 0:53 | 0:11 | <0.001 |
| Premature awakening c | -0.03 | 0.16 | 0.831 | -0.08 | 0.17 | 0.650 |
| Difficulty falling asleep c | 0.15 | 0.11 | 0.159 | 0.09 | 0.12 | 0.447 |
| Difficulty of awakening c | 0.58 | 0.13 | <0.001 | 0.51 | 0.12 | <0.001 |
| Non-refreshing sleep c | 0.51 | 0.11 | <0.001 | 0.42 | 0.11 | <0.001 |
| Disturbed sleep c | -0.06 | 0.12 | 0.643 | -0.09 | 0.14 | 0.530 |
| No. of awakenings c | -0.22 | 0.17 | 0.197 | -0.36 | 0.19 | 0.057 |
| Sleep quality c | -0.12 | 0.12 | 0.323 | -0.04 | 0.13 | 0.779 |
| Sleep efficiency b (%) | -0.56 | 0.92 | 0.545 | -0.68 | 0.99 | 0.494 |
Data from ‘last night shifts’ are presented for 2+2 and 4+4 schedule. The second night shift in 2+2 is compared to the second night shift in the 7+7 schedule (reference). The fourth night shift in 4+4 is compared to the fourth night shift in 7+7 (reference).
Assessed from actigraphy.
Assessed from sleep dairies (response categories: 1-5 with higher number representing poorer sleep).