Circadian Lighting, By Age (03-03-21)

Tian, Chen, and Hu looked at appropriate levels of circadian stimulus (CS) by age.  They determined that “the effect of the CS increased with CCT from 4000 K to 8000 K at the same age as a general trend; however, the CCT of 2700 K shows a higher circadian impact compared to that of 4000 K for the same age groups. . . . In order to provide sufficient CS, the minimum corneal illuminance for children and elderly is 250 lx and 380 lx, respectively, when the CCT of the light source was 2700 K. The minimum corneal illuminance for children and elderly is 150 lx and 420 lx, respectively, when the CCT of the light source was 8000 K. In order to avoid activation of the circadian system, the maximum corneal illuminance for children and elderly is 30 lx and 48 lx, respectively, when the CCT of the light source is 2700 K. The maximum corneal illuminance for children and elderly is 36 lx and 145 lx, respectively, when the CCT of the light source is 4000 K.”  These findings can be used to develop lighting plans, for example.

H. Tian, T. Chen, and Y. Hu.  2021.  “Change of Circadian Effect with Colour Temperature and Eye Spectral Transmittance at Different Ages.”  Lighting Research and Technology, vol. 53, no. 1, pp. 41-53, https://doi.org/10.1177/1477153520923379