THE LIGHT DOCTOR 11: When You Don't Control the Space
Chapter 11 explains how to demand healthy lighting in spaces that you don’t control.
When you leave your home and enter any other building you are exposed to lighting that you didn’t choose, and that has unknown effects on your health and well-being. It is not easy to tell by looking at the lights in a building how much blue light is reaching your eyes, and whether it is too little for daytime, or too much after sunset.
If you are just dropping by the post office to mail a parcel, or a florist to get some flowers, the few minutes you spend there will have little consequence. But if you are going to spend multiple hours in your workplace or a school, or multiple days in a hotel or hospital you should care about the lights to which you are exposed. Or if you happen to work in that post office, or flower shop you should be concerned.
You have the right to ask that every indoor space, where you or your family spend significant time, delivers blue rich light in the daytime hours and blue-depleted light after dark. Whether you are working in a factory, hospital, call center or Amazon warehouse, or trading equities at a Wall Street desk, exposure to conventional blue-rich LED and fluorescent light in the evening hours and at night significantly increases your risk of obesity, diabetes and heart disease, as well as certain cancers. If your elderly parent is in a nursing home, you should also care about the lighting. With properly designed circadian lighting, sleep disturbances can be cut in half, agitation in the residents reduced by 70%1, and the risk of falls reduced by 43%2.
Do No Harm
If you are a young nurse or doctor working overnight shifts in a hospital or nursing home, you should worry about your exposure to blue rich fluorescent and LED lights that are associated with substantially greater breast cancer risk in women and prostate cancer risk in men. But you should also be very concerned about the impact of round-the-clock blue-rich light on your patients. Doing no harm is a fundamental principle of medicine, and while not actually part of the Hippocratic Oath, it was first promulgated in 400 BC by Hippocrates in Of The Epidemics3. Unfortunately, it is now clear that standard hospital lighting is doing much unnecessary harm to the patients under their care.
As Ralph Booth, inventor of the OSIN Loop, tells:
“What drove me to try to elicit change in the lighting industry was my wife getting leukemia 11 years ago. She ended up for weeks on end in isolation rooms before and after her stem cell transplant. I knew even back then that the artificial light in Ellen's room was doing nothing to align her circadian rhythms, I also knew that we were planning a brand-new hospital, and with the knowledge that was known and plain to understand, I naively thought that the critical areas of the new Christchurch Hospital would have lighting that is spectrally tuned to ensure better long term patient outcomes. 11 years on I am sad to say that the isolation rooms have LED lighting that is not spectrally tuned. This got me so frustrated I decided to do something about it, I started OSIN and developed the Loop, a lamp for biological light”.
How hard it is to do anything about it was illustrated by my experience proposing circadian lighting to the President of a Harvard teaching hospital. We had developed circadian lighting that automatically switched from blue-rich day to blue-depleted night with little change in color temperature and had installed them with very positive results in other safety-critical 24-hour operations such as Chevron and Dow Chemical. Naturally we thought that hospitals would be the obvious next target.
Unfortunately, we found that the 130-bed, state-of-the art facility, had just replaced all their lighting with LED fixtures shining blue-rich light around the clock. As a result, the hospital had been awarded certification as a LEED Gold® certified facility in part because of the improved lumens per watt electrical efficiency. It was a point of environmentally conscious pride trumpeted by their marketing department. To the hospital’s credit, their architectural design did maximize daylight access to the building, but then they had undermined the benefits by using blue-rich LED light at night. However, they were just not willing at that time to replace the award-winning LEDs they had just installed.
In that case our timing was off. But we since have been able to install circadian lighting in hospitals. When hospital rooms are equipped with lights that remove blue at night, melatonin levels are restored and sleep is stabilized and improved, all of which help the healing process. For example, Chromaviso has installed circadian lighting in 40 hospitals and 60 senior living homes in Scandinavia. The impact of alternating between blue-rich daytime light and light with no blue content at night has been dramatic. It has reduced the length of hospital stays, and enabled a rapid and significant reduction in manic symptoms in bipolar patients, and a reduction in depression in stroke patients4. It also has resulted in a 20% reduction in staff turnover5.
But despite all these benefits, circadian lighting still comprises less than 0.2% of the lighting market. The traditional way that lights are sold based on aesthetics, lumens per watt efficiency and cost is impeding adoption of this vital new technology. So, it is up to the user and beneficiary – that means you – to learn how to demand circadian lighting in all the places where you spend your time.
How to Get Circadian Lighting Installed
Start by campaigning to get circadian lighting installed where you and your family members spend the most time. To succeed you must understand how lighting decisions and purchases are made. So, let me share what I have learned over the past 10 years about persuading building owners and occupants to install evidence-based circadian lighting, and reap the very real benefits.
Virtually all conventional (non-circadian) lighting sold today is based on the same fundamental technology – the static approximately 450 nm royal blue-chip LED. Lighting has as a result become a commodity with the only differentiation being aesthetics, lumens per watt efficiency and cost. But it is not only objective factors that are at play. Lighting has traditionally been sold through a complex set of carefully nurtured relationships between manufacturers, sales representative agencies, distributors, architects, lighting designers, lighting contractors and building facility managers. Dinners, golf outings and sports tickets foster loyalty, so it is often more about who you know than what you are selling. It can be quite opaque so that most lighting manufacturers have little idea who is actually buying their lights.
The typical buyer of commercial and public building lighting is often not motivated to consider the health and well-being of the building occupants. The performance and bonuses of the building facility manager, and the profits of the building owner, are based on how cheaply they can purchase lighting and how much the lighting will reduce the electrical utility bill. The people who are most affected by the inadequate or harmful LED lighting – the building occupants, and the managers responsible for their performance, health and morale – are rarely consulted on which lights to purchase.
Even if the building occupants ask for “circadian lighting”, there is no guarantee that evidence-based circadian lighting will be purchased. Most often what you will get is a color tuning placebo. So, this is why you need to be knowledgeable and smart in your campaigning for healthy circadian lighting.
Elements of a successful campaign: 1. Education
Most people are completely unaware of the impact of lighting on health, so you need to start with education. The key to education is the WIIFM – What’s in it For Me? And that, of course, depends on whom you are talking to.
Building Owner/Landlord: A building owner has no direct interest in the health of the building occupants. Instead, you need to convince the owner that installing circadian lighting could attract reliable tenants who are willing to pay premium rents. The WIIFM is the opportunity to add a few extra dollars per square foot for leases with circadian lighting because that can have a huge compound effect on the building’s value.
Business Owner/Senior Management: The health of employees affects the bottom line of a business through its impact on their productivity, the rate of sickness/absenteeism and the employee turnover rate. These can together total over $30,000 per employee per year6. Hence the WIIFM is the impact of circadian lighting in boosting employee performance, morale, and health.
Employee occupants: Here the WIIFM is more immediate. You need to explain that circadian lighting improves the quality of sleep, reduces fatigue and the malaise caused by circadian disruption. People are, of course, also concerned about their long-term health and lifespan but that is often more distant and abstract, especially when they are young.
Elements of a Successful Campaign: 2. Know the Pros & Cons of Alternative Solutions
In Chapter 8: Creating Healthy Circadian Light we discussed different ways of providing effective circadian lighting that delivers the correct amount of circadian sky-blue light (440-495 nm) entering the eyes of the people in the room during day and night. This corneal blue irradiance measured in µW/cm2 determines the physiological responses and the health effects of that light, depending on the time of day. As discussed in Chapter 7: Tuning to the Right Wavelength the minimum required daytime dosage is > 20 µW/cm2 and the safe dosage after sunset is < 2 µW/cm2.
So that you can know what these options look like, and understand their pros and cons, we built a Circadian Light Demo which shows three different ways to deliver the required minimum daytime dose of 20 µW/cm2 440-495 nm blue, and the maximum evening dosage of 2 µW/cm2.
The circadian lights on the top row use spectral engineering to minimize the color and CCT change between day and night without changing the lux brightness of the light. The color tuning approach in the middle row requires large changes in the Correlated Color Temperature (CCT) from 6500K to 1800K to provide the same circadian effect. This means a harsh bluish-white light during the day and a yellow-orange light in the evening. The third alternative, shown at the bottom, is to significantly brighten a conventional 4000K royal blue 450 nm peak LED light to provide sufficient blue during the day, and then dim it ten-fold in the evening, both of which conditions can impair visual acuity and comfort. It is also possible, within limits, to combine brightening and dimming with the spectrally-engineered and CCT color tuning options, provided acceptable levels of visual acuity and comfort are maintained, and the correct doses of circadian blue content are delivered.
Elements of a successful campaign: 3. Spec Locks
Lighting decisions in an existing commercial or public building are typically made by the facilities manager, or the lighting contractor hired by the building owner. They are not motivated to spend money on lighting. So, even if you insist on circadian lighting, they will look for the cheapest option that their suppliers call “circadian lighting” whether it is effective or a placebo.
The answer is to know the “spec locks” that will guarantee you actually get effective circadian lighting, and to understand the types of lighting that will meet those spec locks.
Different metrics are required to define the visual illumination of a room versus the circadian health effects of the light on the room occupants.
Visual Illumination
1. Desktop Lux: Most indoor lighting standards are based on desktop or tabletop illumination, also called horizontal illumination. For most workplaces the IES recommends 300 – 500 lux desktop illumination7. As we discussed in Chapter 8: Creating Healthy Circadian Light, lux and lumens are measures of visual brightness largely determined by green and yellow wavelengths, with very little input from blue or red.
2. Lumens of Light Source: The specification of light fixtures required to meet the desktop illumination standard is based on the lumens they produce, the percentage dimming of the light, and the distance of the light fixture from the desktop (remember the inverse square law of light we discussed in Chapter 6: Bringing the Outside Indoors).
Neither of these metrics define the circadian properties of a light.
Spec Locks for Circadian Lights
When ordering circadian light bulbs and light fixtures which avoid the need for excessive brightening during the day and dimming at night, here are two convenient spec locks.
Percent Blue of Light Source: The simplest way to specify circadian light sources is based on the percentage of 440-495 nm wavelengths emitted by the light source as compared to all visible light wavelengths (380 – 780 nm). This can be simply calculated using an Excel spreadsheet from the spectral power distribution (SPD) of the light, which any manufacturer should be able to supply. As a rule of thumb with IES recommended 300 – 500 lux desktop illumination levels, you should look for light sources that emit < 2% 440-495 nm blue at night and >20% blue during the day. This will provide the physiologically required levels of corneal sky-blue irradiance, and a spec lock which your lighting supplier cannot easily circumvent with placebo lighting.
Blumens of Light Source: Blumens are a robust new way to specify light sources for circadian lighting, that parallels the Lumens green-yellow metric for visual illumination. Blumens can be defined as the µW/cm2 440-495nm blue light emitted per 1000 lumens. This is conveniently scaled for lighting designers who specify light sources by lumens. A conventional 4000K 450nm royal blue LED light delivers about 40 Blumens. In comparison, the effective spectrally engineered circadian lights shown above deliver 7 Blumens at night and 76 Blumens during the day, enabling circadian lighting without the requirement for dimming at night.
SCIENTIFIC ASIDE: Other Circadian Lighting Metrics
Those who read the circadian lighting technical literature will find other metrics used by different groups of researchers and lighting specifiers.
Melanopic Equivalent Daylight Illuminance (“Melanopic EDI”)
As we discussed in Chapter 7: Tuning to the Right Wavelength, the melanopsin photopigment in the ipRGC cells in the eye detecting the blue light that synchronizes circadian clocks has a peak sensitivity at 479 nm. The Melanopic EDI metric was derived by right-shifting the sensitivity curve by 11 nm to peak at 490nm aqua blue as a theoretical correction for the yellowing effect of the lens in the eye8. This results in a metric which is sensitive to green light as well as blue.
However, empirical evidence suggests this 11 nm correction does not apply to the normally light-adapted human eye. Studies in fully light adapted people show the circadian peak sensitivity is at 480 +/- 3nm9, and any green light effects fade away in the first 2 hours of light after leaving darkness10.
Currently Melanopic EDI is adopted by standards groups such as the CIE (International Commission on Illumination)11 and Delos WELL12. The recommended daytime light level is a minimum of 250 melanopic EDI lux at the eye. During the evening, starting at least 3 hours before bedtime, the recommended maximum is 10 melanopic EDI lux, and for the sleep environment the recommended maximum is 1 melanopic EDI lux measured at the eye. It is somewhat confusing because melanopic EDI lux is substantially different (about half of) the photopic lux brightness measurement of a typical light.
Circadian Stimulus (CS)
Another metric used by some scientists, and adopted by UL (Underwriters Laboratory, UL DG 24480)13 is the Circadian Stimulus (CS) metric that was derived from the original dark-adapted eye data. It is based on a complex model of the eye and has some fundamental flaws. For example, radically different values are obtained for lights with CCT values below about 3400K as compared to above 3400K. This results in zero blue light below 3400K being classified as more circadian stimulatory than blue-rich light above 3400K, which is the exact opposite of the scientific evidence. Furthermore, we found no correlation whatsoever (R2 = 0.001) between the Circadian Stimulus (CS) values as described in UL DG 24480, and the overnight human melatonin data from people under normal workplace lighting conditions.
Neither of these metrics provide a simple and convenient way to specify circadian light bulbs and fixtures for day and night use, since they provide metrics for eye level light and not for the light source itself. But they are used widely, and you should be aware of them.
Elements of a successful campaign: 4. Applying the Pressure
Armed with the WIIFM education strategy, and the spec locks to ensure you request effective lighting, you are now positioned to make the case for circadian lighting. Like any campaign it will require careful planning, research, and persuasive communication. You will have to identify key stakeholders who will need to be convinced, identify potential allies, and gather support from other users of the space, (for example your co-workers at your workplace, other parents at a school, or other users at a public library).
It is vital that you know the right ask. The International Dark Sky Association mistakenly campaigned for streetlights with less than 3000K CCT believing that it would reduce the light pollution of our skies and the environment. This was based on a 2016 policy statement by the American Medical Association (AMA) about the impact of blue rich light at night14. As I will discuss in Chapter 12: Light Pollution and Protecting Diversity, they were very effective in gaining public support and putting pressure on cities such as Chicago and Los Angeles to change their streetlights. But using CCT as the standard was the wrong ask as it is only weakly related to blue content.
Political Action
Another approach is to campaign for a local ordinance or state law which bans harmful blue-rich light at night. Concerned with the effects of blue rich LED lights on wildlife, the Hawaiian island of Maui in 2023 introduced a new ordinance #5434 which states that “All outdoor lighting fixtures, except for neon, must limit short wavelength content to no more than 2 percent of blue light content. "Blue light content" means the ratio of the amount of energy emitted by the outdoor light fixture between 400 and 500 nm divided by the amount of energy between 400 nm and 700 nm”15. Fines could reach $1,000 a day. In response, the major LED manufacturer Lumileds has developed Nightscape LED technology which can meet the Maui standard16.
Outdoor lighting ordinances with the same intent have been passed elsewhere, and momentum is growing. However, some like the one on Nantucket island are ill-informed because they make the error of requiring outdoor lights to be 2700K CCT or less17.
Now it is time to turn our attention to replacing indoor lighting that is insufficiently rich in blue during the day and too rich in blue at night. It is good to be concerned about wildlife, but even more important to be concerned about the harmful effects of LED lights on our families and loved ones.
Tangled up in Blue
Trying to escape the recent past is the predominant theme of Bob Dylan’s song “Tangled Up in Blue”18. And that is what we are trying to do in a world indiscriminately lit with blue-rich fluorescent and LED light. But there is a $2.5 trillion installed base of lighting which will have to be replaced – and that will take some time.
If you cannot change the lights because you don’t own the building, or cannot influence the owner, there are still things you can do to protect your health.
Using devices to add supplemental sky-blue light during the day, and to filter out the blue wavelengths of light from screens and lamps in the evening hours makes a lot of sense. The problem is that this is rarely done effectively, and there are too many irresponsible marketing claims unsupported by any scientific evidence. So, let’s look at the best practices.
Supplemental Daytime Blue
The ideal way to get the daytime blue light you need for synchronizing your circadian clocks and promoting good health is, of course, to get outside in natural daylight each day. People who see more sunlight each day live longer. A study of 29,518 Swedish women aged 25-64 years followed prospectively for 20 years showed that sunlight exposure had a large effect in reducing deaths from cardiovascular disease and other non-cancer illnesses such as diabetes, more than offsetting any increased risk from skin cancers19. Remarkably, the increased risk from staying indoors and avoiding sunlight was as large as the risk from smoking.
If you cannot get outside, and cannot easily change your inadequate indoor lighting, there are still practical options to provide the blue light you need for daytime health. Desktop lamps such as the Osin Loop20, and the Bios Skyview21, and floor lamps such as the Spectrasol Sunflow22 provide sufficient amounts of daytime sky blue light to protect circadian health. These lamps automatically switch to blue-free light in the evenings based on your local time zone to protect you from circadian disruption. Another option is glass frames equipped with blue LEDS that fit over or replace your eyewear. For example, Re-Timer glasses have been shown to be effective in delaying or advancing circadian melatonin and sleep, depending on whether you use them in the evening or morning23. The problem is that when used unwisely they are equally effective at causing circadian disruption, and their use in night shiftwork is ill-advised.
Blue Blocking Eyewear
Blue blocking glasses are a rapidly growing $30 million/year market24, but most of these products unfortunately block the wrong blue. There are many different color wavelengths in the blue part of the spectrum, as was discussed in Chapter 4: Human Light Interaction, and they have quite different biological effects. 420nm violet blue stimulates alertness, 440 indigo blue can damage the eyes but only at very bright outdoor sunlight intensities, 460 nm royal blue can cure jaundice in newborns and 480 nm sky blue is the key daytime synchronizer for circadian clocks, but disrupts our clocks and health at night.
The best-selling blue blocker glasses are blocking blue mostly below 450 nm. But the peak circadian blue effect is at 480 nm which these clear looking glasses barely touch. The give-away is when the glasses are only very lightly tinted to make them look attractive. In contrast, glasses that remove the majority of the circadian active blue wavelengths (between 440-495nm) are distinctly yellow-orange in color.
There are several vendors, including Cyxus, Rhythm Optics, Swannies and UVEX, offering glasses that block 98% or more 400-495 nm blue light25, but they also block more green light than is necessary in light-adapted people and therefore can impair color vision. The challenge our team at the Circadian Light Research Center, University of Toronto and UC Berkeley addressed was how to balance 440-495 nm circadian wavelength blocking with the best visual performance. The result was BLUESAFE 2426, sold by CircadianEye LLC, which are glasses that maximize the level of lens brightness and functional color vision while providing strong circadian protection.
EssilorLuxottica, the world’s largest eyewear company, sells lenses with a Crizal Prevencia coating which blocks 20% of the light from wavelengths between 400-455 nm, creating a slight blue reflective tint27. They justify this by claiming 425-450 nm wavelengths can damage the eye. This is only an issue in very bright sunlight, but never a problem at indoor intensity levels that are 100 - 1000 times less. Blocking only 20% of these blue wavelengths in bright sunlight seems of small value when any reasonably effective sunglasses will block 50-60% of light from all visible wavelengths. And for indoor use, where 425-450 nm wavelengths present no hazard, upgrading to a Crizal Prevencia coating at a price of approximately $200 puts money in the pocket of the optician with no benefit to you.
But what about the other claims that blue-blocking glasses reduce eye fatigue, digital eyestrain or computer vision syndrome – (the technical name is “Asthenopia”)? Studies comparing computer users with eyewear that blocked 99% of all blue wavelengths between 400 and 500 nm, and the same people with glasses that let through all the blue light, have shown there is no reduction of objectively measured work-related asthenopia with the blue blocking lenses28.
Effective Blue Blocking
Blue blocking glasses can be very effective at preventing circadian disruption in the evening, provided you purchase the correct eyewear that filters out the 440-495 nm circadian potent wavelengths. Even in well-lit rooms, melatonin levels can be nearly fully restored in the evening and during the night29. And gene markers of circadian disruption such as Per and BMal are returned to normal. Sleep latency – the time it takes to fall asleep – is shortened especially in people with sleep disorders, including those caused by jet-lag and shift work.
A single evening’s use of blue blocking glasses doesn’t have much effect on sleep. However, when circadian blue blocking eyewear is used regularly for the 3 hours before bed for more than a week, sleep quality is increased, and glucose metabolism and insulin resistance are significantly improved30.
When blue blocking eyewear in the evening is used in conjunction with 480nm sky-blue light treatments in the mornings, robust effects on performance are obtained. Teenagers who were previously sleep deprived and sleepy in the mornings showed more consistent sleep patterns, improved alertness and better performance on math tests after 3-4 weeks of the combined evening blue blockers and morning blue light treatments31. MRI analysis showed improved brain connectivity, and growth in the dentate gyrus areas of the brain associated with memory formation and learning.
The better option is usually to change the lighting, as that requires no active management, and has less opportunity for error. But, it is good to know that you have options to control your own light diet even if your indoor lighting is far from ideal.
In this chapter you have learned that:
1. You need to be proactive in asking for healthy circadian lighting in the spaces where you and your family spend significant time.
2. Understanding the WIIFMs for stakeholders and decision makers and knowing the spec locks for true circadian lighting, are key to campaigning to get the lights changed in places you do not control.
3. Even in places where you cannot change the lights, you have the option to use blue emitting lamps or eyewear during the day and evidence-based blue-blocking eyewear in the evening.
Preview of next post: Chapter 12: Light Pollution and Biodiversity
We may be entitled to choose the best lighting for ourselves when we are indoors, but it is quite a different matter in the world outside which we share with 8.7 million other plant and animal species. Artificial light disrupts the world’s ecosystems and has detrimental effects on birds and wildlife. Streetlights affect the growth of vegetation and food supplies, by making grasses less tender, and reducing populations of caterpillars and nocturnal insects by up to 50%. Caterpillars in hedgerows in the spring form an integral part of the diet of many songbird chicks, and because of the decline in caterpillars, birds’ survival and growth is negatively affected. The health of adult birds and nocturnal rodents is impaired by the suppression of melatonin and the loss of its protective properties for immunity and cancer control. Tawny owls will not nest in trees lit by electric light, and other owls are also affected.
So, the havoc caused by electric light is not just a human-interest story but hurts all forms of life on our planet.
Schedule
I release a new chapter of THE LIGHT DOCTOR every two weeks by email to my subscribers. The email version will not contain any url reference links, as that can trigger spam filters. The version of the chapter with full references and footnotes will then be uploaded to the Substack website within a week.
I also release a podcast version of each chapter in two parts within a few days after the emailed text version.
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Do you have any recommendations of lighting companies to reach out to that supply circadian lighting. Right now i understand the science but am confused as to who to reach out to to purchase this lighting for home and in clinic. Thanks!