The jury’s still out on human-centric lighting

If someone’s selling you a lighting product that they say will have a particular non-visual effect, take it with a pinch of salt, writes Lux Review’s technical editor Alan Tulla.

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 about human-centric lighting is confusing and sometimes contradictory. Now, at last, some experts have given their initial opinion.

And not just any experts, but the International Commission on Illumination (also known as the CIE) – the body that sets lighting standards globally, and whose recommendations are taken up by national and regional bodies and incorporated into their standards.

Proper light at the proper time

The CIE has issued a short statement titled ‘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.

A lot more research has to be done before firm recommendations can be given about ‘human-centric lighting'

Although the CIE says that drawing conclusions based on knowledge in this field would be ‘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 you a lighting product they say will have a particular non-visual effect, take what they say with a pinch of salt.

More guidance

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 photoreceptor system (including a ‘calculation toolbox’ to facilitate consistent results and allow comparisons with other research).

TC 3-46 WD, on the other hand, focuses on identifying gaps in current knowledge.

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

Pretty much everyone agrees that the right light is good for us and the wrong light is bad. Beyond that, things get a little fuzzy...


  • Lux is hosting a special Lighting for Health and Wellbeing conference in London on Thursday 22 September. It's free for all those associated with the management of buildings services.
  • To view the details and register for a place, click on the conference logo here.