LED (or light-emitting diode) lighting is transforming how we light our homes, workplaces and urban spaces. There is excitement it may help to create workplaces where we feel, and are, more productive. But there are also concerns it could affect our sleep patterns or, even more seriously, our health. Nic Paton attended a workshop that attempted to provide some answers.
It’s probably safe to assume that the town of Silkeborg in Denmark is unlikely to be on the radar for most occupational health professionals. Located at the geographic centre of the country, it is home to some 45,000 Danes, boasts the world’s oldest steamboat in its harbour and is famous for its Silkeborg Langsø fountains, which are lit up each evening for tourists and visitors with colour-changing lights.
And colour-changing lights – this time in its regional hospital – are the reason why the town is being featured in these pages. That is because the lighting at Silkeborg Regional Hospital was recently overhauled by a local lighting company to bring in innovative “human-centric” circadian lighting that is designed to adapt and change, brighten and dim, throughout the day.
Key features include special coloured lighting in areas where employees are working on screens with test data and imagery (for example X-rays, ultrasounds, MRIs and CT scans) to enable them to read and interpret data more effectively than under traditional white strip lights.
Around the hospital, staff can adjust or “tune” their lighting from central touchscreens, and there has even been careful thought given to the sort of lighting that is going to be most effective, and comfortable, for patients and staff in areas such as intensive care, wards and even operating theatres.
This focus on the links between artificial LED (or light-emitting diode) lighting and our circadian rhythms is a seriously hot topic of discussion within the lighting industry right now, with projects such as Silkeborg Hospital becoming increasingly commonplace along with huge interest in the commercial potential of connected or “smart” cities and urban spaces. But you don’t have to Google too hard also to find research raising concerns around how the “blueness” of LED lighting could be affecting our sleep patterns or, even more seriously, heightening the risk of various cancers.
Migraine and nausea
Similarly, a quick (and admittedly unscientific) trawl through the Facebook UK Occupational Health Practitioners group finds advice being sought regularly by practitioners around whether the brightness, glare and/or flicker of LED lighting is potentially contributing to incidence of migraine or even nausea among workers.
As one fairly typical question to the site put it back in 2017: “Has anyone had any experience of employees who are having significant problems with LED lighting in offices or other areas? A client of mine replaced all their office and laboratory lighting in their two premises at the end of 2016/early 17. The ‘colour temperature’, as it is known, is very different. Very WHITE!… One male employee is really struggling with headaches, leading to migraines, nausea and lots of time off… There are lots of grumbles from other staff also.”
So, what is going on here? Is the new LED lighting that in recent years has transformed how we light our homes, workplaces and urban spaces good or bad for our health? Or potentially both? What even actually is “human-centric” circadian lighting? And could a better understanding of the links between light, lighting and our circadian rhythms lead both to better workplaces and better ways of working, especially in areas such as shift or night working?
In an attempt to answer, or at least try to address, some of these questions, a workshop was held in October by ergonomic furniture and accessories companies Wellworking and Bakker Elkhuizen. The event also discussed how workplace design and environment can influence and support cognitive performance.
The discussion around light and lighting was led by Steve Edwards, outdoor application product manager for urban and architecture lighting at lighting company Zumtobel. Edwards first highlighted the fact that, for most organisations, their biggest fixed cost is their people, much more so than even the swankiest modern building. In fact, people make up about 90% of the investment cost put into a business, compared with 9.9% for a building and 0.05% for both lighting and energy respectively.
“So, if you want to create a successful building, if you invest a little bit more money on top of that very small amount of money you will improve the working environment for your most expensive investment, your people. In the end, there are only three things generally that people are unhappy with about their offices: the air, the furniture or chairs, or the light. Those three things, practically, you can do something about,” he pointed out.
He then explained, in broad terms, what LED lighting is. “LED is a technology based on the semi-conductor industry. And this has been a revolution for the lighting industry for the last 15 years. It’s made everything totally different for us. We used to make luminaires, somebody else made a lamp [bulb], somebody else put the lamp inside the fixture. And that was it. And every so often you’d take the lamp out and put a new one in.
“Now, basically, we put an LED light in the ceiling and then the customer really doesn’t need to look at it for 10-15 years. LEDs are evolving and getting better and better, even though there were issues with projects in the past.”
Cool and warm LED light
By “issues”, Edwards was alluding to the “blueness” of LED. LED predominantly emits a light at the blue end of the colour spectrum but, when you put a phosphor cover over it, this turns into a white light (even if the blue light being emitted has only been masked). As a result, early LED lights tended to be notable for their “coldness” – the light emitted often felt much harsher and “bluer” than we were used to from more conventional halogen, incandescent or metal halide lighting, which tends to have a softer, yellower feel.
Many of these technical issues have now been ironed out and, while you can buy “cool” (often branded “daylight”) LED bulbs, for most of us the difference in terms of perception between the old and new lighting is negligible. But the arrival of LED has nevertheless thrown a spotlight on this colour spectrum debate within lighting and, from there, the effect and influence this potentially has on our body clocks, especially the role and use of such artificial light at night.
As Edwards pointed out, even though moonlight is very blue, as humans we evolved predominantly under yellow light. “We all sat in front of a fireplace, that was how we understood what light was, and it was also based on the light quality from the sun.”
One of the innovations of LED, as we see in the hospital in Silkeborg, is that it is “tuneable”; in other words it can be changed and adjusted throughout the day to mimic how daylight naturally changes – and this primarily is what we mean by “human-centric” lighting.
As Edwards explained: “At certain times of day, the brightness of daylight increases and decreases; also the colour temperature of natural light changes. For example, you get a nice red sunset, in the middle of the day it’s much brighter – and whiter – and in the morning when the sun is coming up, because of the way the sun refracts through the atmosphere, it changes in colour. We evolved as a species in an environment where the light changes all the time.
“Yet now we spend all of our time in an environment where the light changes really hardly anything at all. And this is one of the things that could be a problem because of the melatonin that we need. Melatonin is a suppressant and when that comes into your body it depresses another hormone that keeps you awake; melatonin is what makes you start to feel tired.
“The production of melatonin is linked to daylight. If you have blue light at night, for example when you look at your phone this has become an issue, it can affect the way you sleep because it is such a huge blast of the blue end of the spectrum, which is the one that your brainwave doesn’t need to have late at night because it suppresses the melatonin. The way the LED is in your phone, the blue light output is very strong. So, we should all switch our phones off earlier in the evening and not look at them,” he said.
Edwards highlighted research Zumtobel carried out with software developer the Fraunhofer Institute in 2014, polling some 2,000 people about the role and extent of light used in the office spaces in which they worked. Perhaps unsurprisingly, more artificial light was used in winter than summer, with 72% saying their artificial lighting was kept switched on for more than six hours a day during this period. But a third said this was also the case even in spring or summer.
“The thing about artificial light is that it is really in the office space all the time, even in the summertime the percentage of artificially lit space is very high and of course in winter it is higher still. So really there is no other way of getting around it apart from using the technology that we have available now with LEDs to tune lighting within the office space,” said Edwards.
“With LED, we can change the amount of light there is in the space throughout the day, and also the colour temperature of that light. So, in the morning you have increasing light and as you head in toward the evening the lighting level goes down.
“In amongst this, we are changing not only the intensity of the light but also the amount of colour in that light. You can have a nice warm burst in the morning, and then as you head into the mid-morning it turns into a cooler colour, moving between 3000K [kelvin – a temperature measurement of light] and 5000K, which is quite big change. Then over lunchtime, about 1pm, you get this dip. We all experience it. You can suppress that [through light], again it is all about the production of melatonin and when it kicks in at different times.
“It is not about programming people to stay awake; it is more to do with the physiology of who we came from. We’re not really used to sitting in office spaces day in and day out. So the idea is we’re trying to stimulate the brain at certain times of the day by introducing some pretty-much random but perceptible changes to the colour and intensity of the light in the space. And then as you’re heading towards the evening it is nice to get a warmer light, or sometimes cooler light but just less of it,” Edwards said.
Links between light and circadian rhythms
This, in turn, leads into quite complex discussions around how light – daylight or artificial – affects our circadian rhythms. For example, there was the ground-breaking discovery in the 1990s of a previously unknown third “photoreceptor” in the eye – known as the intrinsically photosensitive Retinal Ganglion Receptor (ipRGC) – responsible for melatonin release from the pineal gland, and which has been discovered to be a key influencer on our body clocks.
The challenge, however, for both healthcare and lighting professionals is that, while our knowledge is advancing all the time, this is an area of science and research that is still evolving.
On blue light, for example, there is a growing body of research and, as Steve Edwards made clear, genuine concern. But, how much should we be worried? To what extent does the amount of blue light emitted from our devices, or even lights out in the street, really affect our production of melatonin? Or, in the case of blue light from devices, is it more the cognitive stimulation of the content we’re looking at (especially if it is, say, work emails or something on social media) that is the issue? After all, as already highlighted, the much more extensive blue light from moonlight has been with us for centuries, even if of course it is much further away and diffuse.
Similarly, while there is ongoing research into why shift or night work should be so closely associated with so many negative health outcomes (notably various forms of cancer, cardiovascular disease, diabetes, obesity, stomach problems and mental ill health) it is far from clear what the risk factors actually are here. Is it to do with people being pumped full or artificial blue light overnight? Or is it more down to fluctuating shift patterns, a lack of good-quality sleep, less access to healthy food, less access to daylight generally, reduced opportunities for exercise and so on? Or a combination of all of the above? The jury is still out.
Finally, what about the concerns raised at the beginning of this article by OH professionals around flicker and glare/migraine and nausea and these new forms of lighting? Precisely this question was put to Steve Edwards as the workshop came a conclusion. Is this an issue with LED and, if so, how can you adjust or change the lighting to accommodate for this?
Because of the way they’re constructed, if anything LEDs should be creating less flicker than old-fashioned lighting, argued Edwards. “But I totally agree that, when it comes to LEDs, the issue can be that they are incredibly bright. If you have a single-point source, that light needs to be controlled; that’s why people often prefer having indirect light – because you can spread a lot of the light across a very large surface, which reduces the intensity on any particular surface within the space.
“Of course, some people just don’t like artificial light; that is just a physiological thing. I think that, if that person had any chance of having a more comfortable experience in the office, if they were able to choose the tune light down to an acceptable level, that would be preferable for them,” he said.
Does any of this provide a definitive answer for occupational health professionals about the impact – both positive and negative – of these new forms of artificial lighting and their influence on health and wellbeing? Probably not.
What it does make clear, however, is that there is an important, and ongoing, debate to be had to help employers better recognise and understand the links between working environment (including lighting) and health and wellbeing. It is also clear these new technologies may be able to create working environments that are more accommodating, comfortable and intuitive to work within (such as at Silkeborg Hospital), so enhancing our wellbeing and, potentially, our productivity too.
Yet, at the same time, we need to recognise there is much we still don’t fully understand about the potential consequences the artificial working world we have created, and which we all spend so much time within, has on our bodies, on our health, and on our wellbeing.
As well as being editor of Occupational Health & Wellbeing, Nic Paton is editor of Lighting Journal, the CPD members’ magazine for the Institution of Lighting Professionals
‘Study links night exposure to blue light with breast and prostate cancer’, EurekaAlert!, 25 April, 2018, available online at https://www.eurekalert.org/pub_releases/2018-04/bifg-sln042518.php
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‘Blue light has a dark side’, Harvard Health Publishing, 13 August 2018, available online at https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
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