Table 1.
Characteristics of the included trials
| Study | Study design | Participants (E/C) | Experimental | Control | Time of day | Duration | Outcomes |
|---|---|---|---|---|---|---|---|
| Kohsaka et al., 1999 | Crossover | 8/8 | Moderately bright light (1000 lx) | No light | Morning | 1 h/d, 6 d | VAS |
| O’Brien and O’Connor, 2000 | Crossover | 12/12 | 6434 lx | 1411 lx | 8:00–18:00 | 20 min | VAS |
| Cajochen et al., 2005 | Crossover | 9/9 | Monochromatic light (460 nm) | No light (0 lx) | 21:30–23:30 | 2 h | KSS |
| Crasson and Legros, 2005 | Crossover | 18/18 | Bright light (5000 lx) | Sham exposure | 13:00–14:00 | 30 min | VAS, duration-discrimination task |
| Hansen et al., 2005 | Parallel-group | 19/37 | White light (1800 lx) | Red light (100 lx) | Morning | 93 min/d, 5 d/wk, 2 wk | Harvard Cognitive Battery |
| Rüger et al., 2006 | Crossover | 12/12 | Bright light (5000 lx) | Dim light (< 10 lx) | 12:00–16:00 | 4 h | KSS, VAS |
| Takasu et al., 2006 | Crossover | 8/8 | Bright light (5000 lx) | Dim light (10 lx) | 8:00–24:00 | 16 h/d, 6 d | VAS |
| Viola et al., 2008 | Crossover | 94/94 | Blue-enriched white light (17000 K, 310.35 lx) | White light (4000 K, 421.07 lx) | 8:30–16:45 | ~8 h/d, 5 d/wk, 4 wk | KSS |
| Chellappa et al., 2012 | Crossover | 18/18 | Blue-enriched light (6500 K, 40 lx) | Control light (2500 K, 40 lx) | Evening | 2 h | KSS |
| Santhi et al., 2012 | Crossover | 22/22 | Bright blue-enhanced light (700 lx) | Near-darkness (1 lx) | 19:30–23:30 | 4 h | KSS |
| Sahin and Figueiro, 2013 | Crossover | 13/13 | Short-wavelength blue light (470 nm, 40 lx) | Dark (< 0.01 lx) | 14:30–15:30 | 1 h | KSS |
| Sahin et al., 2014 | Crossover | 13/13 | White light (3000 K, 360 lx) | Red light (630 nm, 210 lx) | Daytime | 2 h | Go/No-go task |
| Leichtfried et al., 2015 | Crossover | 33/33 | Bright light (5000 lx) | Dim light (400 lx) | 7:40–8:10 | 30 min | VAS, Sustained Attention Test |
| Okamoto and Nakagawa, 2015 | Crossover | 8/8 | Short- wavelength light (470 nm) | Darkness | 12:00–16:00 | 28 min | KSS |
| Muench et al., 2016 | Crossover | 18/18 | Mixed blue-enriched lighting (3537 K, 750 lx) | Warm -white control light (2600 K, 40 lx) | 8:00–11:00 | 3 h/d, 3 d | VAS, PVT |
| Borragan et al., 2017 | Crossover | 17/17 | Bright blue-enriched white light (460 nm, 2000 lx) | Dim orange light (600 nm, < 200 lx) | 15:00–17:00 | 20 min | KSS, VAS, PVT |
| Rahman et al., 2017 | Crossover | 16/16 | Standard fluorescent light (4100 K, 50 lx) | Blue-depleted circadian-sensitive light (50 lx) | 16:00–24:00 | 8 h | KSS, PVT |
| Rodriguez-Morilla et al., 2017 | Parallel-group | 12/12 | Blue-enriched white light (440 nm, 469 lx) | Dim light (< 1 lx) | 21:45–23:00 | 75 min | KSS, driving simulator |
| Hartstein et al., 2018 | Crossover | 40/40 | Cool experimental lighting (5000 K) | Warm experimental lighting (3500 K) | 9:00–11:00 | 20 min | Go/No-go task |
| Kazemi et al., 2018 | Crossover | 20/20 | LED (6500 K) | Compact fluorescent (3500 K) | Daytime | 2 h | KSS, Go/No-go task |
| Cajochen et al., 2019 | Crossover | 15/15 | Daylight LED (450 nm, 4000 K, 100 lx) | Conventional LED (4000 K, 100 lx) | 8:00–24:00 | 16 h | KSS |
| Choi et al., 2019 | Crossover | 15/15 | Blue-enriched white light (460 nm, 6500 K, 500 lx) | Warm white light (625 nm, 3500 K, 500 lx) | 10:00–11:00 | 1 h | KSS |
| de Zeeuw et al., 2019 | Crossover | 48/48 | High-mel light (480 nm, 3500K, 100 lx) | Dim light (< 5 lx) | 11:30–14:30 | 3 h | VAS |
| Šmotek et al., 2019 | Crossover | 12/12 | Short-wavelength light (455 nm) | Long-wavelength light (629 nm) | 12:00–15:00 | 20 min | KSS, PVT |
| Studer et al., 2019 | Crossover | 28/28 | Blue-enriched light (458 nm, 876 lx) | Red-enriched light (611 nm, 1063 lx) | Morning | 1 h | Attention network test |
| te Kulve et al., 2019 | Crossover | 12/12 | Bright light (750 lx) | Dim light (5 lx) | Night | 1 h | KSS |
| Yang et al., 2019 | Crossover | 15/15 | Bright light (6000 K, 1000 lx) | Dim light (3600 K, < 5 lx) | Night | 3 h | KSS, PVT |
| Park et al., 2020 | Crossover | 24/24 | LED (4000 K, 150 lx) | Dim light (< 10 lx) | 17:30–24:00 | 6.5 h | PVT |
| Zhou et al., 2021 | Crossover | 17/17 | Blue-enriched bright light (6500 K, 1000 lx) | Normal indoor light (4000 K, 100 lx) | 14:00–14:30 | 30 min | KSS, PVT, Go/No-go task |
E/C: number of participants received experimental intervention/number of participants received control intervention; KSS: Karolinska Sleepiness Scale; LED: Light-emitting diode; PVT: Psychomotor Vigilance Testing; VAS: Visual Analogue Scales.