The jury’s still out on ‘human-centric lighting’, says global standards body

The phrase ‘human-centric lighting’ seems to be everywhere nowadays. I have seen it used to describe everything from bathroom lights and adjustable desk lamps to installations in large hospital wards, multi-storey office blocks and streetlighting.

Much of what is said is confusing and sometimes contradictory. Now, at last, some experts have given their initial opinion.

As many of you will know, the CIE (the International Commission on Illumination), is the body that sets lighting standards globally. Many of its recommendations are then taken up by national and regional bodies and incorporated into their standards.

A lot more research needs to be done before firm recommendations with quantitative values can be given” 

Following a conference in the UK last month, the CIE has issued a short statement entitled Non-visual effects of light – recommending proper light at the proper time. These ‘non-visual’ effects are the influence of light on our circadian rhythms, alertness, sleep patterns and so on.

While the CIE says that knowledge in this field is still ‘premature’, it goes on to say that ‘observations in laboratory and application studies show beneficial effects on human health and performance’. There is general agreement that the non-visual effects of light exposure depend on the spectrum, intensity, duration, timing and temporal pattern of the light exposure. However, they also say that a lack of understanding of the link between the light stimulus and the resulting non-visual response ‘seems to make tailored light application for a desired lighting effect impossible’.

In other words, if someone’s selling a you a lighting product that they claim will have a particular non-visual effect, take it with a pinch of salt.

To give further guidance to interested parties, the CIE will be issuing two new publications. TN003 gives guidance on how to quantify the stimulus of non-visual input in to the human photoreception system (including a ‘calculation toolbox’ to facilitate consistent results and allow comparisons with other research), while TC 3-46 WD focuses on identifying gaps in current knowledge.

In summary, a lot more research needs to be done before firm recommendations with quantitative values can be given about so-called human-centric lighting.


Alan Tulla is Lux's technical editor, and an independent lighting consultant

Comments 1

What this report on the report seems to be saying is that we don't know everything yet. And sometimes things that make intuitive sense turn out not to be true. However, they often are. One thing that seems logical and intuitive is that emulating circadian daylight cycles is "natural" and healthy for humans. How much light, for how long, the precise spectrum, whether it needs to change on an annual cycle (like the sun... but the cycle of what latitude?), or whether it is okay to manipulate these things to produce e.g. sleep or productivity, is all fair game for debate and research. But clearly, living 24x7 under 2700K or 3500K lighting is NOT natural, and likely to have health consequences. First, we start with the ABILITY to manipulate light. Then, we do so in sync with the outdoor, natural world, while studying the difference in effect. Then, we play around with other variations. Make sense?

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