Table 1.
Characteristics of included studies into a meta-analysis.
| Author (year) country | Study design | Sample size | Questionnaire | Outcome | Intervention |
|---|---|---|---|---|---|
| Leppämäki et al. (2003)30 Finland | Experimental (before-after) | 86 | Shift-Work Complaints | Complaints related to shift work | Brief periods (4 × 20 minutes) of bright light (5000 lux) at scheduled times during every night shift over a 2-week period |
| Kakooei et al. (2010)23 Iran | Experimental (before-after) | 34 | Karolinska Sleepiness Scale | Alertness | Bright light (4500 lux) during 2 breaks (21:15-22:00 and 3:15-4:00) in night shift for 4 weeks |
| Boivin et al. (2012)31 USA | Experimental | 14 | Nightcap device | Daytime sleep following night shifts | Bright light (3243±2274 lux) during the first 6 h of each night shift and wore dark goggles during the morning commute home |
| Huang et al. (2013)24 Taiwan | RCT | 46 (in each group) | Insomnia Severity Index | Insomnia | Bright light (7,000-10,000 lux) for ≥ 30 minutes in night shift that continued for at least 10 days. Subjects avoided daytime outdoor sun exposure after work by wearing dark sunglasses |
| Griepentrog et al. (2018)22 USA | RCT (crossover clinical trial) | 43 (in each group) | 1. Stanford Sleepiness Scale 2. Psychomotor Vigilance Test |
1. Sleepiness 2. Number of lapses and errors |
Bright light (1500-2000 lx) for 10 h in night shift |