Boivin 2012.
| Methods |
Trial design: Randomised controlled trial Intervention setting: Police patrol cars Shift system: 35‐day roster. Succession of 8‐8.5 hr shifts according to a predetermined sequence: 3 evening shifts; 2 rest days; 4 day shifts; 2 rest days 7 night shifts (starting at 22:00, 22:30, 23:00, or 23:30 and lasted 8 to 8.5 hr) 6 rest days; 4 evening shifts; 2 rest days; 3 day shifts; 2 rest days Follow‐up period (intervention plus follow‐up): approx. 18 days (5‐7 day preparatory phase; first 48‐hour in‐laboratory assessment; 7 nights of intervention/control; second 48‐hour in‐laboratory assessment) (Washout period): Not relevant* |
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| Participants |
Inclusion criteria: None reported Exclusion criteria: None reported Number screened: Not reported Number eligible: Not reported Number included in our analysis: n = 17 (this includes both RCT participants (n = 15) and RXO participants (n = 2)) Industry: Police officers on patrol Age in years (mean ± SD): 29.8 ± 6.5 (intervention); 30.3 ± 4.1 (control) (n = 17*) Gender: 53% female Country: Canada Month(s) study conducted: not reported, but "season of study...comparable between groups" "Chronotype" score: 49 ± 9 (intervention); 47 ± 12 (control) (mean ± SD; n = 17) *data analysis includes two male police officers who completed both intervention and control conditions, at a 1‐year interval |
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| Interventions |
Intervention: Exposure to full‐spectrum bright, white light via a portable lamp; wearing of orange‐tinted goggles; instructed to keep stable 8 hour daytime sleep episode from 2 hours after the end of the night shift; darkened bedroom windows Shift‐based timing: Light: Night (on‐shift) Goggles: Morning, from sunrise until beginning of daytime sleep episode at home Hours of intervention: Between 22:00 and 05:30 Dose/frequency/duration: Unclear lux, "intermittently" over 8 to 8.5 hour period, "intermittent" exposure per night for 7 nights Control/comparison intervention: No light; no goggles; no sleep instructions (but darkened bedroom windows) |
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| Outcomes |
Outcomes (measurement tool and timing), relevant to current review: Sleep length off‐shift: Outcome not examined Sleep quality off‐shift: Outcome not examined Sleepiness on‐shift:
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| Notes | Funding: Institute de recherche Robert‐Sauvé en santé et en sécurité du travail; Canadian Institutes for Health Research | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information available |
| Allocation concealment (selection bias) | Unclear risk | No information available |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | No information on blinding |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | No information available |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Sleepiness: PVT data: intervention group (n = 8), control group (n = 9). "Nine missing data points were estimated in order to include all police officers in the statistical analysis" "Light exposure during the ambulatory period was analysed independently based on data collected from the actiwatch and the light sensor. Periods during which the device was removed when data were lost due to technical problems for ≥ 3.5 consecutive hours were discarded. For the actiwatch, all data were retained except for two participants (1i, a period of 5 hr and 7i, a period of 5 and 9 hr). For the light sensor, data from eight participants were discarded, for periods ranging from 3.5 to 39 consecutive hours, leaving ≥ 72.9% of data for each participant" |
| Selective reporting (reporting bias) | Low risk | P values given for all statistically significant outcomes but not all of those without statistical significance; detailed data not presented |
| Outcome reliably or objectively measured | Low risk | Sleepiness measured through Psychomotor Vigilance Task and through a VAS |
| Other potential sources of bias | High risk | Mixed study type ‐ 2 participants participated in both groups, in a cross‐over fashion, with a one‐year interval between the two conditions |