Summary of findings 8. Nap interventions (1/2): Nap at night (single nap opportunity) versus no‐nap.
| Nap at night (single nap opportunity) versus no‐nap | ||||||
| Patient or population: Shift workers Setting: Individual workplace Intervention: Nap at night (single nap opportunity) Comparison: No‐nap | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Risk with no‐nap | Risk with nap (single nap opportunity)** | |||||
| Sleepiness during the night shift, postintervention; assessed with Psychomotor Vigilance Task test and Mean Reaction Time test | The mean reaction time during the night shift, postintervention, in the control group was 180.50 ms |
The mean reaction time during the night shift, postintervention, in the intervention group was 11.87 ms faster (31.94 faster to 8.20 slower) |
‐ | 16 (2 RCTs) | ⊕⊝⊝⊝ very low3 | Faster reaction time suggests less sleepiness |
| Sleepiness during the night shift, postintervention; assessed with KSS1 | The mean sleepiness during the night shift, postintervention, in the control group was 6.63 score points |
The mean sleepiness during the night shift, postintervention in the intervention group was 0.13 higher (0.46 lower to 0.72 higher) |
‐ | 8 (1 RCT) | ⊕⊕⊝⊝ low4 | Higher sleepiness score indicates more sleepiness; study design: cross‐over |
| Sleepiness during the night shift, postintervention; assessed with: KSS1 | The mean sleepiness during the night shift, postintervention, in the control group was 6.48 score points |
The mean sleepiness during the night shift, postintervention, in the intervention group was 1.12 lower (1.83 to 0.41 lower) |
‐ | 49 (1 RCT) | ⊕⊕⊝⊝ low4 | Higher sleepiness score indicates more sleepiness; study design: parallel |
| Sleepiness during the night shift, postintervention; assessed with Psychomotor Vigilance Task Test (slowest 10% reciprocal reaction time) | The mean slowest 10% reciprocal reaction time during the night shift, postintervention, in the control group was 2.46 ms |
The mean slowest 10% reciprocal reaction time during the night shift, postintervention, in the intervention group was 0.19 ms faster (0.67 slower to 1.05 faster) |
‐ | 7 (1 RCT) | ⊕⊝⊝⊝ very low5 | Faster reaction time suggests less sleepiness |
| Sleepiness during the night shift, postintervention; assessed with Psychomotor Vigilance Task Test (slowest 10% reciprocal reaction time) | The mean slowest 10% reciprocal reaction time during the night shift, postintervention, in the control group was 2.13 ms |
The mean slowest 10% reciprocal reaction time during the night shift, postintervention, in the intervention group was 0.32 ms faster (0.21 slower to 0.85 faster) |
‐ | 49 (1 RCT) | ⊕⊝⊝⊝ very low5 | Faster reaction time suggests less sleepiness |
| Sleepiness during the night shift, postintervention;
assessed with subjective sleepiness score2 |
The mean sleepiness during the night shift, postintervention, in the control group was 52.02 score points |
The mean sleepiness during the night shift, postintervention, in the intervention group was 16.14 lower (31.37 to 0.91 lower) |
‐ | 9 (1 RCT) | ⊕⊝⊝⊝ very low4 | Lower sleepiness score indicates less sleepiness |
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI); ** In the case of cross‐over trials, the 95% confidence interval reported here is based on an assumed correlation coefficient of 0. CI: confidence interval; ms: milliseconds; RCT: randomised controlled trial | ||||||
| GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1 KSS: Karolinska Sleepiness Scale, a 9‐point scale with verbal anchors ranging from 1: 'extremely alert' to 9: 'very sleepy, great effort to keep awake, fighting sleep'. 2Subjective sleepiness score: VAS and pictorial sleepiness score were significantly correlated and were averaged to create an overall sleepiness score out of 100. 3Downgraded one level due to imprecision (wide confidence intervals), one level due to indirectness (indirect measurement of sleepiness), and one level due to inconsistency (study results inconsistent). 4Downgraded two levels due to imprecision (wide confidence intervals, short observation period). 5Downgraded two levels due to imprecision (wide confidence intervals, short observation period), and one level due to indirectness (indirect measurement of sleep).