Is human centric lighting witchcraft?

Human centric lighting has got Gordon Routledge hot under the cauldron.

In the Middle Ages, if I suggested that a blue light spell could keep you awake at night, or make you perform wondrous things at work, or inflate your waistline, I would have been burned as a witch. (For those of you who don’t have a knowledge of early English history, watch this very humorous Horrible Histories video)


Yet, these days the term human centric lighting is very much in vogue and is suggesting just that. Depending upon which side of the lighting political fence you sit, blue light is either the work of the devil or a new wave in lighting that is going to make us healthier, happier and more intelligent. 

A team of experts working on the Lighting for people project have studied hundreds of scientific papers and drawn a range of sensible conclusions which can be applied in a range of lighting applications, from schools to the home. You can read their recommendations here and the full justification here.

The big issue I have with all the research is that, while I can be convinced of the arguments and can understand the implications, it doesn’t reflect what I experience in my real life. More importantly, it doesn't give me yet another reason to attempt to remove smart phones from my teenage sons late at light in some vague hope they will go to sleep and mean I won't have to drag them from bed in the morning to make the school bus.

There are questions I need answering. Why do I fall asleep when watching TV in bed late at night? Why, after a busy day at an LED lighting show, followed up by some extensive networking in the evening, can I fall on to the bed of my hotel room and sleep happily all night with the lights on? How can many of the office workers in China manage to get their head down during lunch time on the desk for a decent kip with the lights on? Why do I have the annoying tendency to nod off during a presentation on the science of human centric lighting,  no matter what time of day it is?

Perhaps it’s a statistical thing and I’m just like the person who everyone knows who has smoked (I don’t by the way) every day since they were eight and has made it to the grand old age of 92 and is still puffing away on 40 cigarettes a day. Perhaps a certain percentage of us will end up with a light-exposure-related cancer in 50 years due to spending too much time asleep in bed, in front of an episode of House of Cards they never finish watching.

Then there is the school of thought that says we are just like cavemen and should have Paleo lighting. I don’t buy this either as, statistically, cavemen didn’t live very long due to being eaten by something. Perhaps light will be just another drug that prolongs our lengthening lives even further.

What about lighting systems that mimic daylight? It sounds great, but the one thing they miss out is that it is easy to match the colour of daylight over the course of a day, but daylight varies in intensity, and I haven’t seen many trials that have 17,000 lux on the working plane at midday – how would you actually work in such conditions?

As I write this, I can see the social media storm counters starting to build. Instead of fighting it out in cyberspace, get yourself along and join in the debates on the subject at Lux Live. Who knows? If the debate heats up, it might be the first human centric discussion I’ve managed to stay awake through.

  • Human centric lighting will be discussed in detail at this year's Lux Live, which takes place on Wednesday 15 November and Thursday 16 November at ExCeL London. For more information, and to register for free, click here.


Comments 3

If enough people think it's a thing, it's a thing. Certain there is a cadre of luxites lining up behind the notion of the evils of blue light and still more behind the notion that light has a biological effect. Sadly a lot of the published research tends towards the comical and frequently displays a lack of knowledge in at list some of the areas involved including optics, photo-biology, neurology, physiology, image formation and perception. Many things are conflated based only on conjecture: for example that perception and autonomic responses are highly connected, receptors which provide no visual function have no function, bodily sensation of light is entirely a visual function. More often than not, the fact that CIE curves are merely a convention and not an accurate representation of physiological response is ignored. A good place to start would be to throw out all of the research that is tainted by confirmation bias, lack of metrology, insufficient sampling, lack of multivariate analysis, marginal statistical confidence, subjective measures, insufficient qualification of light sources e.g. reliance on CCT, CRI, photopic light intensity, etc which are poor average characterization of spectral content and are in any case measures of subjective visual response not photo-biological response. I once was tasked with the question 'is sunlight hazardous' within the context of radiological safety; short answer, yes. It's at least fair to say that exposure to sunlight has negative effects on humans including observable permanent damage so the notion of lighting that is more or less hazardous to humans is true. To the extent that witch-doctoring is as much an application of mysticism as science, the current state of knowledge about human centric lighting might be accurately described as witchcraft; however, consider the value of modern decendants of alchemy.

You think human centric lighting is witchcraft? I have inside information that within 10 years LEDs will be revolutionized to emit vitamins and minerals - which can be tailored for individual needs. Down on your iron? DALI program it into yourself! A whole world of human centrified, vitamin DALI workers. Lighters will be the Gods they always thought!

I certainly agree with the assertion that there is a lot of opinion not backed by good data about the color of light that is best. Activities vary and the light for them is different, which is sort of obvious to those with more brains than a zuchinni squash. In fact, the whole fixation with sorting led devices and binning the colors has probably delayed the adoption of LED illumination by a few years. REliability, meaning that the source keeps on illuminating and does not fail to illuminate, is more important by far. If the production process is not consistant enough to produce a uniform product then it needs a bit more work. That should be obvious, I would think. I would love to be able to purchase "cool white" LED replacement bulbs that emulated those cool white flourescent lights that we used to have. But most of them instead are that sickly shade of yellow-brown that is called "warm white", more like the glow from a dying fire. OK for sleep inducing but not for detailed assembly work with smaller parts.

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