Table 3.
Subgroup analysis of the efficacy of light intervention on objective alertness
| Subgroups | N | Sample size | I2 (%) | SMD (95% CI) | P-value |
|---|---|---|---|---|---|
| Parameters of light | 10 | 450 | 75 | –0.44 (–0.83, –0.07) | 0.03 |
| Wavelength | 2 | 80 | 7 | –0.39 (–0.86, 0.07) | NS |
| Correlated color temperature | 4 | 178 | 0 | –0.36 (–0.66, –0.07) | 0.02 |
| Illuminance | 4 | 192 | 91 | –0.69 (–1.77, 0.39) | NS |
| Timing of light intervention | 12 | 504 | 75 | –0.29 (–0.66, 0.09) | NS |
| Daytime | 10 | 450 | 79 | –0.35 (–0.78, 0.08) | NS |
| Night-time | 2 | 54 | 0 | 0.03 (–0.51, 0.56) | NS |
CI: Confidence interval; N: number of studies; NS: not significant; SMD: standardized mean difference.