The Commission internationale de l’éclairage, CIE, is releasing new documents on Human-Centric Lighting. The group, known in their English translation as The International Commission on Illumination, notes the types of issues discussed in this forum a couple months ago.

Specifically, their press release states:

Scientists, the lighting industry, lighting designers and other stakeholders in the lighting community have continued to identify options and to design products and solutions that make use of non-visual lighting effects in a beneficial way, despite the fact that the established knowledge in this field is still premature. Among the few points of general agreement is that the non-visual effects of light exposure depend on the spectrum, intensity, duration, timing and temporal pattern (light history) of the light exposure.

The two new documents will address how to quantify the human non-visual response to illumination (presumably in the same sort of statistically average way as the CIE chromaticity diagrams) and how to identify the human factors that are influenced by non-visual illumination. Just to clarify, “non-visual” in this context doesn’t mean invisible or outside the spectral response of the eye. It refers to light sensed by neurons that are not involved in image formation — that are not rods and cones. The primary receptors involved in the non-visual response are called intrinsically photosensitive retinal ganglion cells (ipRGCs). They have a spectral response that overlaps quite significantly with the action spectrum of green cones.

Intrinsically photosensitive retinal ganglion cells detect light and modify human metabolic activity -- the goal of human-centric lighting.

An intrinsically photosensitive retinal ganglion cell, which is the primary receptor targeted by human-centric lighting efforts. Image from Ning Tian, M.D., Ph.D., photographed by Bryan William Jones, Ph.D, via

As with any field on the edge of knowledge, what we don’t know far outweighs what we do know, but the CIE is looking to turn that around. It would be nice to be able to design human-centric lighting based on sound understanding of its physiological effects.