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Correlated color temperature and light intensity: Complementary features in non-visual light field
Raquel Arguelles-Prieto1, Juan Antonio Madrid1,2, Maria Angeles Rol1,2
1Chronobiology Lab, Department of Physiology, College of Biology, University of Murcia, Mare Nostrum Campus, IUIE, IMIB-Arrixaca, Murcia, Spain.
Plos One
|July 12, 2021
Summary
Cooler light (5700 K) caused greater pupillary light reflex (PLR) than warmer light (3000 K), but neither affected melatonin suppression. No correlation was found between PLR and melatonin suppression, suggesting different human intrinsically photosensitive retinal ganglion cell (ipRGC) roles.
Area of Science:
- Chronobiology
- Human Physiology
- Photobiology
Background:
- Disruption of the natural light-dark cycle by artificial light at night can negatively impact human health.
- Understanding the non-visual effects of light is crucial for mitigating health risks associated with chronodisruption.
- Melatonin suppression and the pupillary light reflex (PLR), mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs), are key indicators of light's non-visual effects.
Purpose of the Study:
- To investigate the influence of correlated color temperature (CCT) on melatonin suppression and PLR in humans.
- To explore potential correlations between melatonin suppression and PLR.
- To examine the role of irradiance in conjunction with CCT through mathematical modeling.
Main Methods:
- Experimental assessment of melatonin suppression and PLR in 16 healthy volunteers under two CCT conditions (3000 K and 5700 K) at a fixed irradiance.
- Pupillary light reflex (PLR) was measured as post-stimulus constriction.
- Theoretical modeling was applied to explore irradiance contributions across a wider range of light sources.
Main Results:
- Significantly greater PLR was observed under cooler light (5700 K) compared to warmer light (3000 K).
- No significant differences in melatonin suppression were found between the two CCT conditions.
- No significant correlation was identified between PLR and melatonin suppression.
Conclusions:
- Correlated color temperature (CCT) influences the pupillary light reflex (PLR) but not melatonin suppression under the tested conditions.
- The lack of correlation between PLR and melatonin suppression may indicate distinct roles for ipRGC subpopulations.
- Illumination system design should consider CCT and irradiance interactively, necessitating further research across broader light parameters.
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