Furthermore, no data collection was planned or undertaken by the lighting industry to evaluate the health impact of blue pump LEDs. Instead, there has been dismissal or outspoken opposition by the lighting industry when anyone raises concerns about the serious health problems caused by illuminating our evenings with these blue pump LED lights.

In most trials of a new technology with widespread medical impacts, you can choose whether you want to participate, and serve as a subject in the experiment. However, the choice of whether or not to participate in this experiment was blocked by new Federal regulations which banned the other previously available lighting alternatives such as incandescent and halogen lights, and by state by state bans on fluorescent lighting.

And there are plans by 2028 to increase the dosage and adverse effects of this experiment by progressively tightening lumens per watt regulations which restrict other lighting alternatives, and to amplify the potential harm of these artificial spectrum blue-pump LEDs.

What scientists knew before 2014

Just like ignorance of the law is no defense, ignorance of the published peer-reviewed science is not a valid excuse. Let’s take a look at what was well known and accepted by the scientific community by 2014.

• Light at night disrupts circadian rhythms and causes multiple adverse health effects

• The risk of obesity, diabetes and certain cancers is significantly increased by light at night

• Blue light is much more potent than other wavelengths at suppressing melatonin at night and disrupting circadian clocks

• The blue-rich light at night → melatonin suppression → increased cancer growth pathway had been defined and explains the causal mechanisms.

The warning signs were already there in 2014. It was a known fact that broad introduction of blue-rich LEDs was likely to cause major adverse health impacts. And yet the lighting industry went full steam ahead.

2023: The scientific community reaches a strong consensus

Ten years into this massive uncontrolled experiment, with broad denial from the lighting industry that there is any health problem with blue-pump LED lights, the scientists who have published the most peer-reviewed scientific studies on light and circadian health came together to set the scientific record straight.

These 248 scientists from all over the world reached consensus on 25 statements2

1. Robust circadian rhythms are important for maintaining good health.

Circadian rhythms are most robust when they are tightly synchronized to the natural day-night cycle, and the circadian clocks throughout the body are tightly synchronized with each other. Circadian rhythms under these conditions typically show the greatest amplitude (widest swing between daily maximum and minimum levels). When circadian rhythms are robust, sleep during the night is most restorative, mood, alertness and cognitive performance during the day are enhanced, and the immune system’s capability to ward off disease is strongest.

2. Disrupting circadian rhythms can cause ill-health.

There is a broad scientific consensus that disrupting the human circadian clock system precipitates a wide range of medical disorders. Circadian disruption can have many different types of significant adverse health effects in children, young adults and in the elderly. These include obesity, diabetes, heart disease and breast cancer.

3. Regular daily exposure to daylight enhances circadian entrainment and strengthens circadian rhythms.

Getting outside at a regular time each day, especially in the mornings, and being exposed to natural daylight, is well established as an effective way to keep our circadian rhythms firmly synchronized. In the absence of regular exposure to daylight, our circadian rhythms can become dissociated and flattened and ill-health and susceptibility to disease can result. Regular exposure to daylight strengthens our circadian rhythms and tightens their entrainment by the natural cycle of day and night.

4. Regular daily exposure to daylight can enhance sleep at night.

The average person spends over 90% of their time indoors under twilight levels of lighting. The lack of a strong contrast in light exposure between day and night is a major contributor to the sleep problems that are so common today. Regular daily exposure to outdoor sunlight, or even cloudy overcast daylight, helps deepen and extend our uninterrupted nocturnal sleep.

5. Increasing indoor light intensity during daytime can enhance circadian entrainment and strengthen circadian rhythms.

Since we tend to live indoors in twilight levels of light, our circadian rhythms can become dampened and lose their tight associations with natural day and night. Increasing the brightness of indoor light during daytime hours, especially if it is rich in blue wavelengths, helps to compensate by synchronizing our circadian rhythms to the natural day-night cycle – a process called entrainment. At the same time the entrained circadian rhythms show an increased amplitude – a greater contrast between peak and trough of the daily rhythm.

6. Increasing indoor light intensity during daytime can improve daytime alertness and reduce sleepiness.

Natural light from offices with windows, and bright electric light indoors, especially when it has significant blue content, has an alerting effect, and reduces sleepiness. This combats the natural tendency to drowsiness when we live under twilight conditions.

7. Increasing indoor light intensity at night increases the disruption of circadian rhythms.

Our eyes and brain are highly sensitive to light during the nighttime hours (from sunset to sunrise), and the disruptive effects on our circadian rhythms get more pronounced the brighter the light intensity. This effect is exacerbated by lights with high blue content such as LEDs or fluorescent lights.

8. Increasing indoor light intensity at night increases the suppression of nocturnal melatonin production.

Melatonin is the pineal hormone that plays an important role in signaling the darkness of night to all the cells of the body and their internal circadian clocks. When people live outdoors in the natural world, melatonin rises at sunset and falls at dawn. But when we use electric lights, we suppress the melatonin signal and may shift it. Our internal circadian clocks interpret electric light at night as a shift in the timing of day and night. The brighter the electric light at night the more suppressed and shifted is the melatonin rhythm.

9. Repetitive and prolonged exposure to light at night bright enough to cause circadian disruption increases the risk of breast cancer in women.

The first reports were published in 2000 showing a significantly increased risk of breast cancer in women exposed to light on the night shift. Since then, several national and international scientific bodies have reviewed the considerable accumulated evidence from hundreds of human epidemiological and animal model studies. After reviewing all the evidence, the WHO International Agency for Research on Cancer, and the National Toxicology Program of US National Institutes of Health have linked light exposure at night to circadian disruption and to the significant increase in the rate of new breast cancer cases.

10. Repetitive and prolonged exposure to light at night bright enough to cause circadian disruption increases the risk of obesity and diabetes.

A substantial body of evidence has accumulated in recent years showing up to twice the risk of obesity and diabetes in people who are exposed to light at night, either by leaving the lights on in the bedroom at night, or by working on night shifts. These effects can start developing even after only one night of light exposure.

11. Repetitive and prolonged exposure to light at night bright enough to cause circadian disruption increases the risk of sleep disorders.

Light at night has three key effects on sleep. First it alerts and stimulates our brain which makes it harder to fall asleep or stay asleep. Second it shifts our circadian clocks so the timing of when we can easily fall asleep is shifted. Third it disrupts our circadian clocks and the architecture of the various sleep stages such as REM and non-REM sleep, so that sleep is disrupted and not as fully restorative.

12. The sensitivity peak of the ipRGC melanopic receptors in the human retina is approximately 480nm in the blue part of the visible spectrum.

A major breakthrough in circadian science was the discovery of the intrinsically photosensitive retinal ganglion cell (ipRGC) receptors in the eye that detect the blue wavelengths in light. The peak sensitivity of these ipRGC receptors is to sky-blue light at about 480 nm.

13. The most potent wavelengths for circadian entrainment are 460-495 nm blue light near to the sensitivity peak of the ipRGC melanopic receptors.

While the ipRGC receptors have their peak sensitivity at about 480 nm, they can sense a broader range of blue light photons. Blue light is most potent in synchronizing human circadian clocks to the environmental day-night cycle, a process called “entrainment”, in the 460-495 nm range near the 480 nm peak sensitivity.

Blue-enriched (460-495nm) light in the evening (during the three hours before bedtime) …

14. disrupts nocturnal sleep more than blue-depleted light at the same intensity

15. phase delays the circadian system more than blue-depleted light at the same intensity.

16. disrupts circadian rhythms more than blue-depleted light at the same intensity.

When you are exposed to light containing potent 460-495 nm blue wavelengths in the evening after sunset, it shifts and disrupts your circadian rhythms and impairs your sleep at night. We are sensitive to an even broader range of 440-495nm blue during overnight hours. The solution is to use blue-depleted light at night – i.e. light without those disruptive blue wavelengths – rather than conventional LED lights which are rich in blue. This greatly reduces the risk of shifting our circadian clocks, and disrupting our sleep.

17. Exposure to 460-495nm blue light at night suppresses melatonin production.

Because we are so sensitive to blue light at night, a broad range of blue wavelengths can suppress pineal melatonin production. The strongest suppression occurs with blue light wavelengths between 460 and 495 nm. These blue wavelengths interfere with the signaling of natural darkness by melatonin and undermine the important protective effects of melatonin at night, such as suppressing cancer cells in the body.

18. Exposure to 460-495nm blue light at night disrupts circadian rhythms.

These same 460 - 495 nm blue wavelengths during the nighttime hours have the largest effect in disrupting circadian rhythms. These blue wavelengths are 20 times more potent than full spectrum white light which contains all the wavelengths of the visible light spectrum. Exposure to even a small amount of blue light at night is highly disruptive to circadian rhythms.

Practical Applications

The 248 scientific experts were then asked about the practical implications of the well-established science of circadian-light interactions and reached a consensus on the following statements:

19. Light used in the evening (during the three hours before bedtime) should have as little blue content as practically possible.

We become increasingly sensitive to the blue content in our electric lights as the evening progresses. Thus, it is important to replace your lights in the places you spend your evenings, such as the family room, bathroom and bedroom, with lights that have very little or no blue content.

20. The risk of circadian disruption during the three hours before bedtime can be reduced either by 1) dimming indoor lighting which may compromise the ability to perform visual work tasks, or 2) reducing the blue content of indoor lighting maintained at the intensity required for visual tasks.

There are two ways of addressing the problem with blue-rich light during the evening hours. Since what matters is the total number of blue photons that you are exposed to per second, you can dim your existing conventional lights significantly to reduce the total amount of light to which you are exposed. The problem is that this may make it hard to read, or difficult for your children to do their homework. Alternatively, you can replace your current lights with low blue content lights so you can maintain visual illumination at your preferred levels.

21. The blue content of light entering the eyes is much more important in determining circadian health outcomes than the correlated color temperature (CCT) of the light source.

Changing the color of lights, measured as correlated color temperature or “CCT”, has been touted by the lighting industry as a way to reduce blue content. Unfortunately, this is a highly misleading marketing strategy which does very little to address the problem. At the key 460 - 495 sky-blue wavelengths high CCT and low CCT electric lights can have very little difference in blue content, as they are all based on blue-pump LEDs. It is far more important to know the blue content of the lights that you are using than their CCT or color appearance.

22. Increasing the energy efficiency of lights is desirable, but not if it increases the risks of causing circadian disruption and serious illness.

Since the widespread introduction of LED lights in 2013, the lighting industry has been focused on promoting and improving the energy efficiency of LEDs. It has been the key selling proposition which has enabled blue-enriched LEDs to dominate the lighting market. While maximizing energy efficiency is, of course, desirable, failing to address the adverse health impact of lumens/watt efficient blue-enriched LEDs is a much more significant problem. These blue-rich LEDs can increase your exposure to blue light at night, and accelerate the electric circadian havoc and ill-health caused by electric light.

23. LED lights with high 460 - 495nm blue content should carry the warning label “maybe harmful if used at night”

There was strong consensus among the 248 leading scientists researching the impact of light on circadian rhythms, that the evidence is now clear than blue-enriched LED lights with high 460 - 495 nm blue light content should carry a hazard warning label related to their use at night. This is justified by the increased risk of obesity, diabetes, heart disease and several types of cancer that are associated with exposure to excessive blue wavelengths at night.

24. There is now sufficient evidence to support the widespread introduction of circadian lighting that adjusts light intensity and blue content across day and night to maintain robust circadian entrainment and health.

There was also strong consensus that the lighting industry needs to transition to circadian lighting where the brightness of light and its blue content are varied by time of day. During the daytime hours indoor lights should be rich in sky-blue wavelengths, and during the nighttime hours from sunset to sunrise these sky-blue wavelengths should be removed.

25. There is significant variation in individual sensitivity to light, therefore circadian lighting should be optimized where possible using personalized solutions.

Some people are much more sensitive to the blue content of light than others, and it is important to adjust the blue content in electric lighting to make allowance for these more sensitive people. Furthermore, the orientation of our circadian clocks in relation to day and night may differ somewhat between individuals. Some of us are early rising “larks” and then fall asleep earlier in the evening. Others are genetically more sensitive to blue rich light in the evening and their sleep patterns may be delayed. These differences between people are reduced by regular exposure to natural outdoor light during the day.

What can you do about it?

The fastest way this changes is for enough people to know what their lights are doing and to start asking for better. The 248 of us can lay out the evidence. We cannot create the demand. Only you can do that, one informed choice at a time.

The lighting industry has known about this for years. Regulators have been slow to act. But you do not have to wait for either of them to change the light in your own home.

You can also join the movement to alter the regulations to enable more healthier light alternatives. Visit: https://circadianlight.org/campaign/background-on-the-healthy-lighting-campaign/

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure for everybody, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

In seven clinical trials, in USA, UK, Holland, and Japan, with a total of over 1,500 Alzheimer dementia patients, correctly designed circadian lighting protocols have been shown to have a broad, sustained positive impact on dementia care.

What is correctly designed circadian lighting?

We are not talking about varying the correlated color temperature (CCT) of the light with the time of day. That is a placebo offering with very little real value. It is not the visible color of the light that matters.

What matters with light is its spectral composition. In other words, does the lighting deliver ~480 nm blue rich light starting at the beginning of each day, and remove all ~480 nm blue during the evening and night? And does it do this with the effective circadian wavelength dosages and timing?

For example, you have probably seen on the internet, AI slop feeds, or lighting company marketing materials, cartoon images of circadian lighting that get it all wrong. Some of them use time-lapse images captured above the arctic circle during mid-summer when the sun never sets. It is an attractive image, but it is totally misleading.

First, it shows correlated color temperature (CCT) varying with the time of day. Second, it fails to recognize that gradually building up to peak levels of 5500K - 6500K CCT light in the middle of the day (12 noon - 2pm) doesn’t work1. Sleep is not improved, circadian clocks are not robustly entrained, health benefits are not obtained. Third, people need to be in darkness at night, not yellow light.

Benefits of True Circadian Lighting

When the right spectrum is provided at the right time of day, circadian lighting measurably slows the progression of the key symptoms and events that trigger decline in early Alzheimer patients2.

1. Cognitive decline slows with working memory improved, and MMSE scores elevated by 5% in a multi-year follow-up. The Mini-Mental State Examination (MMSE), also known as the Folstein test, is a 30-point questionnaire used extensively by healthcare professionals to screen for cognitive impairment and track its progression.

2. Functional independence is preserved with the rate of decline in activities of daily living slowed by 53% under long-term circadian light treatment.

3. The rate of falls by care home residents is reduced by 38 to 43% eliminating the single most common trigger for emergency transfers to hospital or advanced care.

4. Depression is substantially reduced preventing the mood deterioration that accelerates the family decisions to move residents out of assisted living.

5. Agitation – a primary driver of care escalation -- drops below clinical thresholds within months.

6. Sleep quality normalizes - reducing the nocturnal disturbances that exhaust families and staff. But note this benefit only occurs when blue-rich light commences early in the morning.

The beauty of this intervention

The intervention is passive, requiring no patient cooperation and, because it operates continuously, it compounds its benefits over time.

The evidence is now sufficient to regard circadian lighting, not as a comfort amenity, but as a clinically validated tool for extending the function, mood and health of patients with mild cognitive impairment.

Benefits build over time

Importantly, the effects of circadian lighting compound over time. You are not going to see the full effects if you only test it in a short trial.

• The relative improvement of functional limitations in Alzheimer patients has a time dependent effect, growing larger with each year of exposure to circadian lighting .

• Circadian rhythm stability continues to improve significantly as the weeks of circadian lighting progress. These improvements continue long after the initial mood improvements appeared.

• Reductions in depression and agitation, progressively improve in studies lasting for six months or more. This is in contrast to pharmaceutical treatments which tend to lose their effectiveness in dementia patients over time.

In conclusion

In the USA about 1 million people with Alzheimer's disease or other dementias live in residential care settings. And only a handful so far have installed true circadian lighting. These days most residents are kept under constant spectrally-deficient LED light

Another 6 million Americans over the age of 65 who have dementia, are being cared for at home. And the lights used at home are mostly conventional unhealthy LEDs.

It is paramount that we deliver true effective circadian lighting to this population to improve their quality of life and their ability to participate and enjoy the activities of daily living as long as they can.

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure for everybody, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

An interesting case is that of arthritis. The most common forms of arthritis are osteoarthritis, which is associated with a loss of cartilage in joints, and rheumatoid arthritis, which is an autoimmune disease that causes inflamed joints.

John Ott, wrote the 1973 best seller, Health and Light, which brought broad public awareness to the effects of ultraviolet light wavelengths on human and animal health. He tells a story of how when he started spending much more time outdoors, his osteoarthritis radically improved and he had no longer any need for steroid injections into his hip joints. His arthritic hip, which had not felt well for three or four years and had required a cane and large doses of aspirin—improved dramatically without any change in medication.

He explained this as an effect of ultraviolet light on his eyes because he had recently broken his eyeglasses which normally blocked all UV wavelengths, and he was no longer wearing them. However, there is another more probable explanation. People who are exposed to plenty of sunlight have higher vitamin D3 levels and significantly reduced osteoarthritis. In other words, vitamin D deficiency which is a consequence of a lack of natural UV exposure in daylight, is an important reversible contributor to osteoarthritis1 2.

However, a recent study shows this is not true for rheumatoid arthritis. Using the UK BioBank database, Li and colleagues tracked the incidence of rheumatoid arthritis in 358,540 people over several years, and found that those who had more than 2.5 hours of daylight exposure each day had a significantly increased rate of rheumatoid arthritis3. The risk linearly increased with even more daylight exposure.

Now, to put this in perspective, only 1% of the total population of people studied developed rheumatoid arthritis. So, this is an adverse effect seen in only a few people.

Sunlight, although its broad effects are highly beneficial, should be seen as similar to a medication which depends on the dose and is subject to inter-individual sensitivities.

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

This has enabled consensus lighting targets to be developed1, such as requiring:

• Daytime illumination with a minimum of 250 melanopic EDI lux at the eye, measured on the vertical plane at approximately 1.2 m height (eye level when seated).

• Evening illumination, starting at least 3 hours before habitual sleep time, with a maximum of 10 melanopic EDI lux

• Night illumination, during the sleep period itself, with less than 1 melanopic EDI lux — essentially darkness — to minimize any suppression of melatonin

Such industry standards can be very helpful, so that everyone can work towards the same goals. But they can also slow down progress, because of the slow multi-year process of reaching expert consensus on a standard, and the reluctance to open up that debate again, once a standard has been agreed upon, and published.

Consequences of the Melanopic EDI standard

The spectral sensitivity curve for Melanopic EDI has a peak at 490 nm, close to the blue - green color border, with a significant amount of its circadian-active light spectrum falling into the green wavelengths of the solar spectrum. So, this might lead you to conclude that green light, as well as blue, synchronizes circadian clocks.

However, the melanopsin photopigment in the ipRGC cells in the eye, that detect the blue light that synchronizes circadian clocks, has been directly measured with a peak sensitivity at 479 nm2, not 490 nm. The difference lies in the fact that the Melanopic EDI metric was not derived empirically (i.e. there was no direct measurement or experimental verification). Instead it was derived by right-shifting the melanopsin spectral sensitivity curve (peaking at 479 nm) by 11 nm so that it peaked at 490nm, as a theoretical correction for the yellowing effect of the lens in the eye. This results in a metric that is sensitive to green light as well as blue.

Not so fast

For years evidence has been accumulating that, under normal lighting conditions, green light does not synchronize circadian clocks.

1. Eyewear filters transmitting green light do not suppress melatonin3:

Professor Casper and Shadab Rahman at the University of Toronto created special eyewear that filtered out only the blue and violet wavelengths below <485 nm (<10% transmission) and allowed all the green, yellow, orange, and red wavelengths to reach the eyes of their human subjects. When they sat under bright fluorescent office lighting all night (600-1,000 lux tabletop), without wearing the filtering eyewear, the nocturnal melatonin rhythm was highly suppressed. However, when the subjects wore the blue & violet light filtering glasses, the melatonin rhythm was fully restored to the levels seen under darkness at night.[i] This meant that green light had no effect, and the circadian signal that suppressed melatonin was comprised of only blue (and possibly violet) light.

2. Lighting filters that only block 430-500 nm blue suppress melatonin4

My colleagues and I created special filters that would remove narrow wavelength bands from the white light spectrum. We conducted a series of overnight studies with fully light-adapted volunteers exposed all night to electric lights fitted with these different wavelength filters. This enabled us to narrow down the critical circadian-active wavelengths to a range of blue light between 430 nm and 500 nm. The green wavelengths from the light were not blocked and shone through, but this had no suppression effect on melatonin levels.

3. The circadian potency curve in light-adapted people has no green energy5

Next we built different LED lights, all that appeared white, with many different permutations and combinations of color wavelengths. This permitted us to compare the suppression of overnight melatonin by very different LED lights, all delivering white light at the same brightness (lux) level. Because the mix of wavelengths differed for each LED light, we could tease out which individual wavelengths were the most effective at suppressing melatonin and impacting circadian clocks. This allowed us to define the light-adapted circadian blue signal which had a narrow band of sky-blue wavelengths with a peak effect close to the peak 479 nm sensitivity of melanopsin. There was no green effect in this circadian sensitivity curve.

4. The green effect fades away after 2 hours of adaptation to light6.

Early studies in 2000, which had initially found an effect of green of melatonin levels studied dark-adapted people sitting in pitch darkness who then were exposed to monochromatic (single color) lights for 30-90 minutes. However, in 2022, when researchers at the Division of Sleep and Circadian Disorders at the Brigham and Women’s Hospital in Boston repeated these experiments, but extended them to six hours of monochromatic light, the green effect disappeared within 2 hours and the peak sensitivity after they became light adapted was close to 480 nm (480 +/- 3 nm) for both melatonin suppression and for resetting the circadian clock.

5. Pure 480 nm blue light is far more effective than any other color wavelength7

480 nm sky blue light is so effective, you need much less of it to reset circadian clocks than polychromatic white light, where the energy is distributed across multiple violet, blue, green, yellow, orange, and red wavelengths. A monochromatic 480 nm pure blue light delivering 12µW/cm² to a person’s eyes has been shown to have almost the same circadian clock resetting power as 3000 µW/cm² of broad-spectrum white light. After correcting for pupil constriction caused by the much brighter white light, the 480 nm pure blue light delivered the same circadian resetting with about 5% of the energy used by the white light. This tells us virtually all the circadian action is in the sky-blue wavelength band and virtually none in the green.

What do we conclude?

These five different types of empirical evidence indicate that the 11 nm right-shift correction built into the melanopic EDI sensitivity standard does not apply to the normally light-adapted human eye. In fully light-adapted people the circadian peak sensitivity is at 480 +/- 3nm, and any green light effects fade away in the first 2 hours of light after leaving darkness.

Hence the Melanopic EDI standard applies only to the first two hours after we awake in the morning after sleeping in a dark bedroom. The green effect is a transient which fades away within two hours after dawn or switching on the lights.

So the Melanopic EDI standard needs to be revised to reflect the normal conditions of being fully light adapted But because the current Melanopic EDI is so deeply embedded in standards and calculators, it will take time for it to be formally modified into a more realistic assessment of circadian sensitivity under normal indoor lighting conditions.

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

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PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

Not only do they lose the lifespan- and healthspan-extending benefits of regular morning daylight exposure, but they are exposed to artificial lighting that gets progressively less healthy as we age.

It is not the lights that are changing. Rather it is the progressive yellowing of the lenses in our eyes, and the unfortunate uneducated choice of 450 nm blue pump LED lighting that makes it increasingly unfit for purpose the older you get.

Readers of this Substack newsletter, and my book THE LIGHT DOCTOR, will know that the timing and the amount of 480 nm sky-blue light that enters your eyes each day is critical for your health and well-being. 480 nm is the peak sensitivity of the blue detecting receptors in the eye1 - the intrinsically photosensitive retinal ganglion cells (ipRGCs), and exposure to this wavelength in the morning robustly synchronizes our circadian clocks and boost our health and well-being.

Outdoor daylight provides a rich source of this critical 480 nm blue light. But, as we have discussed, conventional LED lights instead have a royal blue spike at about 450 nm and a big dip in their spectrum at around 480 nm - the so-called cyan gap. The chart above shows that the 450nm blue from conventional LEDs has only 70% of the effectiveness of 480 nm blue tuned to our biological need. The reality is that these LEDs are designed for lumens per watt energy efficiency without any consideration of their negative health impact.

In contrast, healthy circadian lighting uses a 480 nm blue peak during the day that is tuned to the spectral sensitivity of the circadian system.

The problem gets worse as you age

These failures in the design of conventional LED lights are a problem even when you are young. But as you age this mistuning of blue light gets has even worse effects. As the years pass by the lenses in our eyes progressively grow yellower. As this happens, these lenses within our eyes block more and more of the lower wavelength light in the violet and blue range. This effect is most pronounced the lower the wavelength. Hence the reduction in the transmission of 450 nm wavelengths is much larger than that of 480 nm wavelengths.2

We can read from the chart below that by the age of 70, only 23% of 450 nm blue light reaches the retina of the eye. In contrast, 42% of 480 nm light falls on the retina, because it is less impacted by lens yellowing.

The combined effects get worse as you age

When you multiply the relative circadian clock synchronizing effectiveness of 480 nm versus 450 nm light by the wavelength dependent effect of the ageing lens, you will find that at age 70 only 16% of 450 nm light gets through to the retina, whereas 42% of 480 nm blue light reaches the blue detectors in the 70-year-old person’s eyes.

By using 450 nm blue-rich conventional LED lighting we are placing our elderly in a depressing world of unhealthy biological dimness, thereby hastening their “shuffle off this mortal coil” as Shakespeare would say.3

And as I would say “it is time to change your lights” and the lights of your elderly loved ones.

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

My brother and I played outdoors most of the time, and when we were indoors we had no screens in the house (not even a TV). The windows were plain glass with no UV or infra-red filtering. And ultraviolet filtering car windscreens had not yet been widely introduced.

In the evenings our home was lit with incandescent light bulbs and was warmed in winter by coal fires in the fireplace, both emitting copious amounts of red and infra-red wavelengths.

The Healthy Light We Have Lost

Children today live in a very different world. Their “energy-efficient” e-glass windows at home and in school block ultraviolet and infrared light from entering their living spaces, as shown in the chart.

They spend their time under LED lights and viewing LED-lit screens, neither of which provide ultraviolet, violet, far-red or infrared light.

Their basketball courts and athletic tracks are often indoors under harsh LED lights with very little natural illumination.

Most homes built or renovated in recent decades likely have modern windows with a good degree of UV protection, especially against UV-B rays. They also block the far red and near-infrared wavelengths at the other end of the solar spectrum.

The result is an artificially narrowed light spectrum depicted in the diagram below.

Ultraviolet light blocking was introduced into window glass long before infrared blocking. Prior to 1930 all window glass freely allowed UV-A to pass through, although the more damaging UV-B (under 315 nm) was largely blocked. Then between 1930 and 1950 glass manufacturers introduced UV-blocking glass, not for any health reasons, but instead to prevent textiles from fading and furniture from discoloration.

Two methods were developed. The first was to increase the iron oxide content of glass which provided strong UV absorption between 300 and 380nm. The second was to create laminated glass with an interlayer of polyvinyl butyral (PVB), an optically clear polymer which blocks all UV up to 400 nm.

Older buildings may still have clear glass windows, but replacement windows, newly constructed buildings and vehicles usually block UV up to 400 nm, and red above 700 nm thus fundamentally altering the solar spectrum indoors.

What they are missing

We know deep violet light (360-400 nm) is critical for eye health and for prevention of myopia (short sightedness). Yet modern windows block these critical wavelengths below 400 nm.

A misguided definition of ultraviolet light is at the heart of the issue, now that we understand how important are the non-visual effects of light.

UV-A is officially defined by the international Commission on Non- Ionizing Radiation Protection (ICNIRP) as having a wavelength between 315 nm and 400 nm.1 Yet that same august body, the ICNIRP, defines visible light as having a wavelength between 380 and 780 nm.2 You can see the problem. The ICNIRP is defining the wavelengths between 380 and 400 nm as both UV and Violet.

Modern windows filter UV-A out of daylight because it penetrates the lens of the eye, and has been thought to be primarily responsible for cataracts. But if you block all wavelengths up to 400 nm as most modern windows currently do, then you are depriving people of health-promoting deep violet light that stimulates Opsin 5 in the eye. Concerns about the harmful effects of longer wavelength 360-400 nm UVA may have been overstated. For example, UVA below 360 nm increases the risk of cataracts, but there is little evidence that 360-400 nm violet light causes cataracts.

Infra-Red Deprivation

Not only do modern windows block UV light, they also block infrared. This is a significant health issues because we are increasingly realizing the importance of having far-red and near-infrared wavelengths in our light spectrum. Recent studies show that adding even low doses of infrared light in indoor spaces can have significant benefits.

At University College London, in a windowless media lab, solely lit by blue-pump LED ceiling lights, Professor Glen Jeffrey and Edward Barrett investigated the impact of adding infrared-rich incandescent light.3 One half of the workstations were provided with a 60-Watt desk lamp for two weeks; the other half had no additional illumination. The incandescent lamps added about 190 µW/cm² (0.7 J/cm2/hr) of far-red and infrared. To study the effects of the 8 hours per day workplace exposure they used color vision tests, because, the cones of the eye are packed with ATP energy-producing mitochondria that are boosted by far-red and near-infrared light.

Significant improvements in both blue (tritan) and red (protan) color vision were seen in the subjects who were given the incandescent lights. Remarkably this benefit continued for more than six weeks after the incandescent lights were removed, suggesting that the infrared didn’t just boost ATP production, but had also triggered the longer lasting effects of protein synthesis. The control subjects who remained only under blue-pump LED lights showed no such color vision improvements.

Larger doses of near-infrared for shorter periods of time also have significant effects. Charlotte Roddick and colleagues at the University of British Columbia used a within-subject double-blind design.4 151 university students were studied for an hour under conventional LED lights with no infrared, and then for an hour under the LED lights supplemented by far-red and infrared peak wavelengths of 735 nm, 875 nm, and 960 nm. The lighting conditions were presented in random order, and the subjects couldn’t visually tell the difference between the two lighting conditions.

Although the lighting looked the same, the addition of near-infrared was found to have a significant calming effect, measured objectively by a decrease in heart rate variability, as compared to LED lights without any added infrared.

Bring back clear glass windows

The huge amount of evidence now accumulating that the full spectrum of natural daylight promotes health and increase longevity5, leads us to the conclusion that we need to reconsider the glass we put in our windows. There is a strong argument o bring back clear glass especially for people living in daylight-deprived latitudes. Spending time close the window can have significant benefits for health and well-being, but only if the window glass lets through the natural daylight spectrum

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

Public health experts have been correct about the relative risks of driving versus flying, but they have been very wrong about the risk of sunlight exposure. For the last 50 years public health educators have urged us to avoid too much sunlight, because of the increased risk of skin cancers, such as malignant melanoma.

Now, a new study from the University of Edinburgh, Scotland has quantified for the first time the relative risks of spending time outside versus staying indoors. The bottom line is the difference in relative risk is of the same order of magnitude as flying versus driving.

Coming full circle

The benefits of sunlight for treating disease were not systematically studied until 1893. That was when a Danish medical scientist named Niels Ryberg Finsen, who suffered from chronic ill-health, started systematic studies of heliotherapy. His work, which earned him the 1903 Nobel Prize in Physiology or Medicine, showed that certain conditions such as lupus vulgaris, a skin manifestation of tuberculosis, responded well to sunlight.1

The widespread excitement following Dr Finsen’s work led to hundreds of clinics being opened in Europe and North America to treat patients with sunlight. Hospitals were built with balconies where patients could be wheeled out in their beds each day for bathing in the sun.

Heliotherapy mania reached a peak in 1928, the year that the first antibiotic, penicillin, was discovered by Alexander Fleming. The British newspaper of record, The Times, published a 48-page supplement on Heliotherapy extolling its virtues and widespread use. The enthusiasm wasn’t just limited to natural daylight exposure; ultraviolet lamps were widely promoted for their healing powers. And the medical community largely dismissed any concerns about adverse effects of UV light. In 1929, the editors of the Journal of the American Medical Association (JAMA) in response to an inquiry, wrote “There is no evidence available that exposure to the sun predisposes to epithelioma of the skin” (a term then used for skin cancer).2

By the 1950’s dermatologists became increasingly concerned about the increased incidence of malignant melanoma and other skin cancers related to excessive sun exposure. This led to a concerted effort to educate the public about the skin cancer risk of excessive exposure to the UV in sunlight.

Fear of skin cancer should not keep you indoors

For the past 50 years we have been told that sunlight causes skin cancer, and we should avoid exposure to the sun. But the real risks of staying indoors have not been properly balanced against the risks of spending time outdoors.

We have previously discussed how people who spend more time outdoors live longer. For example, playing golf regularly can add 5 years to your lifespan (See Substack March 11, 2025). But the relative risks of outdoor versus indoor lifestyles were not precisely quantified.

Now a new study of over 400,000 people, using the UK Biobank data, shows that the increased risk of skin cancers from ultraviolet light exposure is very small compared to the reduced risk of cardiovascular disease and other causes of death when people spend time outdoors.

They divided 419,007 adults of white European ancestry into three groups 1) Low UV exposure, 2) Moderate UV exposure and 3) High UV exposure based on the time they spent outdoors, the latitude of where they lived, and their use of solariums, UV lamps, and sunscreen ointments. Deaths from skin cancer showed no clear dose-response relationship between the Low, Medium and High UV groups. However, the overall death rate, and the deaths from cardiovascular disease and other non-skin cancers, were substantially increased in the low UV group who spent the least time outside.3

To clarify the impact they projected what would happen if everyone in the study was in the high UV Exposure Group , and then if everyone was in the Low UV Exposure Group

• For every malignant skin cancer fatality saved by staying indoors, 75 deaths from other causes occur because of lack of exposure to the healing power of natural daylight.

• For every extra malignant skin cancer fatality caused by increased UV exposure, there would be 134 lives saved from all other causes of death, including heart attacks, and non-skin cancers (e.g. breast, prostate and colorectal cancer)

This study is still in the peer-review process and so it may be subject to final revisions, but it does suggest there is about a 1:100 ratio between deaths caused by UV exposure and deaths saved by UV exposure.

Everything we do in life has a risk. So, it is a question of picking the most favorable risk. And regular exposure to the full natural outdoor light spectrum, including the invisible ultraviolet and infrared, is clearly the risk that we should take.

For further background information

The quickest way to understand the importance of healthy lighting and outdoor daylight exposure, and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

Fortunately, that very bad idea died, and dark-dependent lifeforms on earth dodged that bullet. But as Llewellyn Rockwell said “never underestimate the power of a bad idea. It must be refuted again and again.”

Now a California company, Reflect Orbital, Inc. backed by Silicon Valley venture capital, has applied for permission from the Federal Communications Commission (FCC) to launch and operate non-geostationary satellite space-based solar reflectors intended to direct artificial illumination onto the nighttime surface of the Earth.

Their proposal SAT-LOA-20250701-00129 represents a fundamentally new category of space activity: intentional large-scale modification of the natural terrestrial light–dark cycle from orbit.

Unlike existing satellite constellations, which produce light pollution as an unintended consequence, the proposed system is expressly designed to introduce directed illumination into the nocturnal environment. This would have devastating effects on the health of humans and the other 8.7 million species which are evolution-optimized to live under the natural 24-hour light-dark cycle.[i]

I have written a formal comment to the Federal Communications Commission (FCC) to meet the March 6th 2026 public comment deadline urging them to take into consideration the considerable health harms caused to humans and other species on Earth by reflecting sunlight to illuminate the earth at night, and to reject this application by Reflect Orbital.

Here are some of the points I made:

Adverse Impact on Human Health and Well-Being

For the first 10,000 generations of human existence, our ancestors were exposed to bright natural light during the day and very low levels of moonlight or starlight at night. Artificial lighting in the from of wood fires and candles was dim and blue-free. In recent years, especially since the introduction of widespread LED lighting, there is growing awareness of the adverse health impacts of being exposed to light at night. Over 20,000 peer-reviewed scientific research papers have shown the link between light at night, circadian disruption, and increased risk of obesity, diabetes, heart disease, immune disorders, psychiatric illnesses and certain forms of endocrine sensitive cancers such as breast cancer, prostate cancer and colorectal cancer. There is now substantial evidence for the link between light exposure at night and disruption of circadian and metabolic systems and failure of cancer-suppression mechanisms.

It is not only the light within buildings at night that has adverse consequences, but also the light emitted by artificial lights outdoors. There have been increasing efforts to make outdoor lighting less harmful and find a correct balance between the safety and convenience of outdoor nighttime lighting and the avoidance of health harms. This includes an emphasis on carefully focusing on where the light beams fall and avoidance of spillover.

Light reflected from satellites because of the distances involved cannot be adequately focused and controlled and will result in large areas being illuminated outside specific targets.

Impacts on the other 8.7 Million Species on Earth

We are part of a highly complex interdependent global ecosystem that we only partly understand. All life forms on Earth evolved to operate most successfully under the natural day-night and seasonal cycles conferred by our rotating planet. Increasing outdoor nighttime light levels above 0.2 lux of bright moonlight disrupts the feeding and breeding behaviors of millions of species, and most of the time, natural light levels are much less at night.

Disrupted Food Webs

Nature is comprised of complex sets of food webs with food chains that are critical to the survival of each species. Not every species in a food chain has to be directly disrupted by light at night. All it takes is for some microbes, plants, insects, or animals in the food chain to be affected, and everything else above them in the food chain suffers.

The primary producers in terrestrial food chains are plants that use the sun’s energy to photosynthesize inorganic nutrients (e.g., phosphates, nitrates) into organic food (e.g., leaves and flowers) that other species can eat. The primary consumers are the herbivores that eat the plants (e.g., caterpillars or grasshoppers). Secondary consumers are the carnivores that eat the primary consumers (e.g., songbirds or mice). Above them in the food chain are the apex predators such as hawks, which feast on the secondary consumers such as songbirds or mice. The players at each level, of course, depend on the ecosystem and climate.

Light at night significantly impacts these food chains. Crops alongside illuminated roads grow rapidly but fail to flower, and the normal development of soya beans is disrupted.[ii] Some species of grass grow more rapidly while others are suppressed, changing the nature of the food supply to the detriment of some species and the advantage of others.

Similarly, primary consumer populations are disrupted by unnatural levels of light at night, both because of changes in food supply, and because of direct effects on their development. Caterpillar populations under streetlights are reduced by almost 50% in the hedgerows and by 33% in the grass verges of country roads.[iii] This reduces the food supply to secondary consumers such as the songbirds that nest in those hedgerows.

Aquatic Food Chains

In aquatic food chains, the primary photosynthesizing producers include algae, which live near the surface where they can harvest the most sunlight. Their primary consumers are zooplankton, thousands of species of small animals, including shrimp and other crustaceans, which are highly sensitive to light and hide deep in the water during the day and come up to feed on the algae at night. The secondary consumers are the fish that eat the zooplankton.

Unnatural levels of light falling on any body of water at night forces the zooplankton to stay deeper below the surface, so they are less visible to the fish that prey on them.[iv] This behavior starves the fish of their primary food supply, and at the same time, allows the uneaten algae to bloom, contaminating the surface of the water. Fish populations, as a result, plummet.

Sensitivity to Light

Worldwide, around 30% of vertebrates and more than 60% of invertebrates are nocturnal.[v] Nocturnal species are generally much more sensitive to light at night than day-active species. Their eyes are often adapted to detect lower light levels at the expense of visual resolution.

The spectral composition of moonlight is quite different from sunlight.[vi] The peak energy is deep in the violet at around 400 nm, compared to sky blue 480 nm peak energy in sunlight – although the peak of the daylight spectrum can vary with weather conditions. It is therefore not surprising that nocturnal species gauge the brightness of light from a different range of spectral wavelengths than humans. Whereas humans experience maximum brightness at 555 nm in the green, nocturnal species are often more sensitive to shorter wavelengths sometimes down into the ultraviolet. Even small changes in lunar brightness from a new to a full moon can trigger critical reproductive and developmental effects.

Reflected sunlight from orbiting satellite mirrors, besides raising brightness way above natural moonlight, introduce unnatural spectra into the nocturnal landscape. We have only scratched the surface of how each of the millions of nocturnal species with diverse spectral sensitivities are affected. This greatly impacts biodiversity because unnatural nocturnal lighting fundamentally changes the photic environment.

Some species are attracted by light, others are repelled by it, yet others may have their life-critical behaviors and physiological systems disrupted. Let’s look at some examples of unnatural nocturnal light effects:

• Circadian, Circalunar & Circannual Disruption: Both day-active and nocturnal species rely on the precise timing of natural day-night cycles, whether they are the daily sunrise and sunset, the approximately monthly waxing and waning of the moon, or the changes in day length and night length with the seasons of the year. Disruption of these natural light-dark cycles impacts metabolism, immunity, and risk of cancer and other diseases, just like humans. However, the sensitivity to low levels of light is much greater. For example, in nocturnal rodents it takes only 0.03 lux of light (moonlight levels) to suppress melatonin significantly.[vii] Furthermore, unnatural levels of light at night affects feeding behaviors, and reproductive success to a greater extent than it does in mankind.

• Spatial Disorientation & Navigation: Many nocturnal species use the moon or stars to navigate. Unnatural light sources can obscure their view of the sky, or provide false signals. As a result, they may fail to find feeding grounds, or to mate and reproduce.

• Attraction: Some species are attracted to light, and others are repelled by it. About a third of insects approaching outdoor lights die soon after due to collision, overheating, dehydration, or predation”.[viii] Millions of birds die each year after colliding with buildings, attracted from miles away by the lights.[ix]

• Loss of Dark Adaptation: As we discussed, nocturnal species are highly sensitive to light, and may take hours to regain complete dark adaptation after coming close to artificial lights. This temporarily blinds the creature and interferes with its ability to find nutrients or avoid predators.

• Bioluminescence: Fireflies and certain other species use bioluminescence to emit light flashes to attract mates. Outdoor unnatural light may mask these signals and interfere with reproduction.

In 2023 Travis Longcore at the University of California, Los Angeles, Institute of the Environment and Sustainability, undertook an exhaustive exercise to document the spectral sensitivity of 320 species of terrestrial wildlife that could be affected by the nighttime lighting of California’s highways.[x] These included Spiders, Insects, Amphibians, Reptiles, Birds and Mammals. The lesson learned is that the diversity of responses to light is enormous. There is no ideal one-size-fits-all solution to lighting the natural landscape – other than returning landscapes, wherever possible, back to the lighting conditions of the natural world.

Conclusion

The allure of this engineering challenge has blinded its proponents to the considerable harm this endeavor will cause to the health and wellbeing of life on earth. The regular 24-hour cycle of day and night is fundamental to the evolution of lifeforms and biological systems. A large body of biomedical science shows that even relatively minor disruptions of the timing and intensity of light at night can have profound adverse effects.

Current FCC satellite licensing frameworks primarily evaluate:

• radiofrequency interference,

• orbital debris,

• spectrum coordination.

They do not adequately address optical emissions deliberately directed toward Earth.

The natural day–night cycle is a shared planetary resource. Authorization of intentional orbital illumination represents a decision with irreversible environmental and biological consequences extending far beyond telecommunications policy.

Accordingly, approval without environmental and biomedical impact reviews would establish precedent allowing commercial alteration of the global night environment absent comprehensive regulatory assessment.

I requested that the Commission:

1. Require full Environmental Assessment (EA) or Environmental Impact Statement (EIS);

2. Evaluate circadian and ecological consequences of orbital illumination;

3. Coordinate review with NASA, NOAA, NSF, DOI, and public-health agencies;

4. Defer authorization pending development of optical-emission standards for satellite systems.

Submitting your own comment to the FCC

You can express your concern by registering at the Federal Communications Commission (FCC) and filing your own comment. The Reflect Orbital FCC application code is SAT-LOA-20250701-00129 S00711
This first application by Reflect Orbital Inc. seeks Launch and Operating Authority to deploy and operate one non-geostationary orbit (NGSO) satellite. They aim to follow it up with many other earth-illuminating satellites.

The FCC public comment process is a little complex, but useful guidance can be found at: https://aas.org/posts/advocacy/2026/02/how-submit-comments-satellite-applications-fcc

For further background information

The quickest way to understand the importance of healthy lighting and the value of nocturnal darkness is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

[i] https://www.smithsonianmag.com/smart-news/how-russian-space-mirror-briefly-lit-night-180957894/ Archived January 4 2024 at https://perma.cc/7ZJQ-J2VV

[i] Moore-Ede, M (2024) THE LIGHT DOCTOR: Using Light to Boost Health, Improve Sleep and Live Longer. Circadian Books.

[ii] Sinnadurai, S. (1981) High pressure sodium lights affect crops in Ghana. World Crops 33: 120–122. And: Briggs, W.R. (2006) Physiology of plant responses to artificial lighting: Ecological Consequences of Artificial Night Lighting (eds C. Rich & T. Longcore),pp. 389–412. Island Press, Washington, DC, USA

[iii] Briggs H (2021) Light pollution from street lamps linked to insect loss. https://www.bbc.com/news/science-environment-58333233 Archived January 5 2024 at https://perma.cc/8797-GHDT

[iv] Moore MV et al (2006) Artificial Light at Night in Freshwater Habitats and Its Potential Ecological Effects. Chapter 15 in Ecological Consequences of Artificial Night Lighting. Eds. Rich C and Longcore T. Island Press, Washington DC.

[v] Hölker, F. et al. (2010). Light pollution as a biodiversity threat. Trends in Ecology & Evolution, 25, 681–682.

[vi] Breitler J-C (2020) Full moonlight-induced circadian clock entrainment in Coffea arabica. BMC Plant Biol. 2020; 20: 24. doi: 10.1186/s12870-020-2238-4

[vii] Grubisic M et al (2019) Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates Sustainability 2019, 11, 6400; doi:10.3390/su11226400

[viii] Minnaar, C.; et al (2015). Stacking the odds: Light pollution may shift the balance in an ancient predator-prey arms race. J. Appl. Ecol., 52: 522–531. And: Owens, A.C.S.; Lewis, S.M. (2018) The impact of artificial light at night on nocturnal insects: A review and synthesis. Ecol. Evol. 2018, 8:11337–11358 And: Cited by Zhou, C. et al (2023) Artificial Light at Night (ALAN) Influences Understory Plant Traits through Ecological Processes: A Two-Year Experiment in a Rubber Plantation in China. Ecologies 4: 704–713. https://doi.org/10.3390/ecologies4040046

[ix] US Fish and Wildlife Service. Threats to Birds: Collisions - Nighttime Lighting https://www.fws.gov/story/threats-birds-collisions-nighttime-lighting Archived January 6 2024 at https://perma.cc/JNL3-F5XC

[x] Longcore T (2023) A compendium of photopigment peak sensitivities and visual spectral response curves of terrestrial wildlife to guide design of outdoor nighttime lighting Basic and Applied Ecology 73: 40–50 https://doi.org/10.1016/j.baae.2023.09.002

[i] https://education.nationalgeographic.org/resource/biodiversity Archived January 4 2024 at https://perma.cc/4RYG-GLE9

The Illuminating Engineering Society (IES), funded by the lighting industry through memberships subscriptions, trade shows and publications, has just published a Recommended Practice under the framework of the American National Standards Institute (ANS I) which disputes the need for daytime circadian lighting. It is titled Supporting the Physiological and Behavioral Effects of Lighting in Interior Daytime Environments (ANS I/IES RP-46-25)2.

Buried in the middle of this report, in section 5.1.1 Mistaken Use of Circadian in the Physiological Effects Lexicon (page 18), there are a series of statements which dismiss the need for circadian lighting during the day. However these are very misleading, and make it appear that circadian lighting is not required during the daytime.

Entrainment must be robust to promote good health

IES: “It is typical for sighted individuals to be entrained to 24 hours, even under lighting conditions considered poor, such as in dimly lit offices and areas with degraded lighting systems.”

IES “There is no evidence for generally occurring non-entrainment of individuals living or working in environments with poor lighting conditions.”

Effectively what the IES is claiming is that any light, even that of poor quality, is sufficient for entraining human circadian rhythms. This is analogous to saying that “any food, even junk food, can prevent hunger” It’s a very low bar, and totally ignores the health consequences of poor lighting (and junk food), and fails to recognize the improved health outcomes from high quality circadian light (and nutritious food).

Entrainment merely means that circadian rhythms maintain a 24 hour cycle, and are not free running, and that is true for most people. However, health and well-being require the circadian rhythms in multiple physiological functions to be aligned precisely and correctly. And this happens only with “robust” entrainment by strong light-dark cues.

As we have shown (see THE LIGHT DOCTOR pp129-143) a daytime dose of 440-495 nm blue in excess of 20 μW/cm² is required to optimize circadian phase and circadian outcomes such as sleep and cognitive performance. Most conventional LED lighting does not provide this, unless it is uncomfortably bright.

IES “low daytime light levels, if followed by darkness at night, are sufficient to entrain the clock.”

The only citation offered by the IES to support this claim is a study using ground squirrels!

The obvious problem for humans is that it is often not sufficiently dark at night, because of light pollution and lack of education about restricting light at night. Entrainment is such a low bar because you can be entrained but still have significant health consequences from being exposed to light during the evening and nighttime hours - especially if daytime lighting is inadequate.

Circadian Amplitude is Important

IES “While the benefits of light on the robustness of the circadian oscillation (its amplitude) have been postulated, measurement of circadian amplitude in humans is difficult, and there are no published studies demonstrating the benefits of enhanced circadian amplitude.”

To the contrary, the amplitude of the melatonin rhythm is strongly dependent on the intensity of light during prior daytimes, and the amount of melatonin produced at night is key to restoration and repair of body tissues, and suppression of cancer cells. The consolidation and duration of sleep is enhanced by consistently timed prior daytime light exposure. Reduction in amplitude can also be easily measured in renal electrolyte circadian rhythms and is associated with ageing, illnesses and weak environmental lighting cues.

Lack of daylight is a big problem which requires circadian lighting

IES “for individuals with access to daylight in, or from, an outdoor environment, there is no ecological justification to change either electric light quantity or spectrum for circadian entrainment.”

What this statement does not take into account is that daylight diminishes in intensity rapidly as you get farther away from windows. There are now many studies which show that people who are near windows sleep better, than those who are at a distance from the nearest window. Also, hospital patients with a wide range of medical conditions have a shorter length of stay when they are exposed to daylight by being close to a window. Psychiatric patients who are provided rooms with SE facing windows get out of hospital in half the time as compared to those patients with the same conditions placed in rooms with NW facing windows. The only way to compensate for insufficient daylight exposure is to use circadian lighting.

Are the opinions of the authors of the IES Recommended Practice representative of the experts in this field?

The IES selected a few scientists on their Light and Human Health Committee to prepare this Recommended Practice, but were they representative of the expert knowledge in this field?

As you may know, we recently conducted a consensus study with 248 of the world’s leading scientists who had published the most papers on the interactions between circadian rhythms and light. Purposely we avoided making this a hand-picked group. Instead, we invited every scientist in the world who had published at least four scientific peer-reviewed publications in this field in the past 10 years to participate.

These 248 scientists came to a clear consensus on multiple statements3 including:

1. Robust circadian rhythms are important for maintaining good health

2. Regular daily exposure to daylight enhances circadian entrainment and strengthens circadian rhythms

3. Regular daily exposure to daylight can enhance sleep at night

4. Increasing indoor light intensity during the daytime can enhance circadian entrainment and strengthen circadian rhythms

5. LED lights with high 460 to 495 nm blue content should carry the warning label “may be harmful if used at night.”

6. There is now sufficient evidence to support the widespread introduction of circadian lighting that adjusts light intensity and blue content across day and night to maintain robust circadian entrainment and health

Does this IES RP meet ANSI Standards?

Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and other criteria have been met by the standards developer.

As ANSI explains “Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution”

It would seem this process was not followed since the conclusions reached are so out of step with the recent consensus of 248 leading scientists in this field!

Further Reading

The quickest way to understand the importance of healthy lighting is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

REFERENCES

And the Design Light Consortium (DLC), which sets standards for architectural lighting, has placed their new minimum requirement at 125 -145 lumens per watt.

Of course, I am kidding about sunlight being banned, but, in contrast to modern LEDs, it only delivers about 93 lumens per Watt of radiant power. Way below the new DOE lighting standards.

What is going on?

Archaic Metric

The problem is the 100-year-old metric used to assess the efficiency of light. Lumens per Watt measures the light intensity in a very narrow band of mostly green and yellow wavelengths which our eyes perceive as brightness. This V(λ) (VLambda) curve, plotted above in green, only accounts for a small sliver of the solar spectrum (in red)

In contrast, the sun produces numerous light wavelengths critical for health across a wide band of visible and invisible light (300 - 2,500 nm). Most of this light producing solar energy is treated as “wasted” Watts by the misguided Lumens/Watt efficiency formula.

These “wasted Watts” are actually producing light in many wavelengths that are essential to health. But the wrong-headed DOE regulations regard human health as superfluous, and a total waste of energy!

Death knell for healthy lighting

If you try to build electric lights designed to replicate some of the health benefits of natural light, you run into a thicket of regulations and building codes designed by people unaware of, or unconcerned with, the vital health promoting qualities of light. Healthy electric lights that provide the day-night control of circadian blue, or provide the near-infrared which boosts mitochondrial energy production, will be banned in the USA in 2028 (which is only two years away) - because they cannot meet the new Lumens/Watt minimum requirements.

Policies aimed at conserving energy, and reducing global warming, are progressively ramping up the Lumens per Watt targets. The result is LED lighting that is progressively getting less healthy.

Taking Health from Humans to Power AI Engines

So here is the deal. We are taking healthy lighting away from humans to save on electricity consumption. But we are using all those energy savings (and more) to power data farms that drive the growth and health of artificial intelligence.

If I were a conspiracy theorist, I would argue this is convincing evidence of an evil plot. However, I actually think that this is plain human ignorance, and lazy-minded group think by the lighting industry and their federal regulators.

The Urgent Need for a New Healthy Lighting Product Class

This brings me to the conclusion I have previously discussed. We need a whole new product class of General Wellness (i.e. healthy) lighting products that is unencumbered by archaic Lumens per Watt rules. Lighting that uses wavelengths for health that are not counted by, or restricted by, the Lumens per Watt formula.

Science and creative engineering are unlocking the secrets of light and health. We need to enable innovation in lighting unconstrained by nonsensical rules, standards and regulations.

We have petitioned the US Department of Energy to create a new Product Class. To learn more and join the campaign visit https://circadianlight.org/campaign/

Further Reading

The quickest way to understand the importance of healthy lighting is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber.

Upgrade to Annual Paid Subscriber

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription

Upgrade to Annual Paid Subscriber

If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

The first take home lesson from this chart is that virtually every visible color and invisible light wavelength has specific biological effects.

It is hard to see the all the detail so I have zoomed in one part of the chart below.

Readers of THE LIGHT DOCTOR newsletter know that the conventional blue pump LEDs that dominate the lighting market today are highly deficient in many of healthy wavelengths of light during the day (such as the 480 nm blue that syncs circadian clocks), and while providing harmful doses of blue light in the evening hours. They are also totally deficient other critical wavelengths, such 700-900 nm near-IR.

You might think the solution would be to use full spectrum electric lights that mimic the natural solar spectrum and provide as many wavelengths as possible.

Unfortunately, it is not so simple. Natural daylight is typically 100 times brighter than indoor electric light and delivers 100 times more total light energy across the full UV, visible and IR spectrum . Outdoors the visual brightness of light (photopic illumination) may vary between 5,000 and 50,000 lux or more. Indoors we live under 50 to 500 lux measured at the table top, and even less ( 40-60%) entering our eyes. We cannot tolerate much brighter light in closed indoor spaces because of glare and reflections.

While sunlight has sufficient energy at every wavelength to trigger all the physiological pathways and responses shown in Stig’s graphic chart, electric light usually does not have sufficient energy to trigger the whole gamut. This is because each physiological response depends on receiving a sufficient dose of light (i.e. fluence or radiant exposure) at each specific wavelength.

So you have to choose your target.

As an example, synchronizing the human circadian clock requires more than 20 microwatts per square centimeter (>20 µW/cm²) of sky-blue light between 440-495 nm entering our eyes (see pp.130-134 in THE LIGHT DOCTOR). Sunlight on a bright sunny day delivers on average 50,000 lux outdoors which translates to approximately 70 microwatts per square centimeter for every nanometer (70 µW/cm² /nm) across the visible light spectrum. So, sunlight delivers 70 µW/cm² x 55 nm = 3,850 µW/cm² of sky blue light which far exceeds what is needed to keep our circadian clocks in synch. Even on a cloudy overcast day with only 5,000 lux of daylight entering the eyes, the amount of sky blue wavelengths is 385 µW/cm² which is more than sufficient.

However, indoors at my desk I have a typical indoor level of 300 lux of illumination on the desktop, and only 120 lux of that enters my eyes. If I use a broad spectrum light with all wavelengths at the same level of intensity, then that 120 lux of light will only deliver 0.167 µW/cm² per nm, or a 440-495 nm blue total of 9.2 µW/cm². This is well below the 20 µW/cm² minimum dose of sky-blue light required to safely synchronize my circadian clocks.

There are two solutions if I am confined indoors and want to make sure I receive an effective indoor daytime dose of sky-blue light:

1. Triple the brightness of the full spectrum electric light to about 900 lux which would provide an adequate circadian dose of 27.5 µW/cm² 440-495 nm sky-blue light. But that would probably give me a headache because of the glare from an uncomfortably bright light.

2. Use a spectrally-engineered light during daytime hours which delivers a spike of >20 µW/cm² of sky-blue light without needing to increase the lux level of visible brightness more than is comfortable. An example of the Max Blue daytime light from Korrus OIO is shown in the chart below

The bottom line is to be sure we are having the intended effects, we need to understand the minimum effective dose (i.e. fluence or radiant exposure) for each desired wavelength-dependent physiological effect in humans under normal indoor work and home environments.

Of course, by far the best way to get your daily dose of full spectrum light is to get outside in the mornings. But there are many people, because of sickness, infirmity, or occupation cannot do this. For them switching to circadian supportive lighting indoors is critical for their well-being.

Further Reading

The quickest way to understand the importance of healthy lighting is to read my book THE LIGHT DOCTOR.

Get Your copy of THE LIGHT DOCTOR

Become an Annual Paid Subscriber to THE LIGHT DOCTOR newsletter

and get The Ultimate Circadian Bedroom Lighting Package as a free gift of healthy light and restful sleep with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter.

Upgrade to Annual Paid Subscriber

Here are the benefits you unlock with each new Paid Annual Subscription to THE LIGHT DOCTOR newsletter beginning today:

• Ultimate Circadian Bedroom Lighting Package mailed to your home (for USA residents only*), including:

  • Latest edition of THE LIGHT DOCTOR book.

  • Blue-free book reading light - so you can read the book in the evening without any blue light exposure

  • Two A-19 automatic OIO circadian light bulbs which automatically cycle between blue-rich days, blue free evening lights and red night lights – so that your lighting is always healthy

  • OIO loop which enables you check any light fixture or bulb to see if it is providing healthy light appropriate for the time of day or night.

  • Hallway and bathroom blue-free night lights which automatically switch on when it is dark - so you safely walk to the bathroom without switching on the lights

• Unlimited year-long access to all THE LIGHT DOCTOR newsletters, podcasts and premium resource materials.

• Catalog of evidence-based healthy lighting products from reliable vendors.

The Ultimate Circadian Bedroom Lighting Package is the ideal gift for family and friends (or yourself) so you can bless them with healthy light and restful sleep,

Give yourself and your loved ones the gift of healthy bedroom lighting with each new Annual Paid Subscription to THE LIGHT DOCTOR newsletter

If you are already a paid monthly subscriber and wish to take advantage of this offer please go to the subscribe page and upgrade your subscription to an Annual Paid Subscriber. a

Upgrade to Annual Paid Subscriber

a Thanks again for supporting our campaign for healthy lighting

PLEASE NOTE: *The Ultimate Circadian Bedroom Lighting Package can only be shipped to USA residents because of electrical compatibility and current tariff fees. Residents of other countries who sign up for an Annual Paid Subscription to THE LIGHT DOCTOR newsletter will be shipped a signed copy of the latest edition of THE LIGHT DOCTOR.

We regret this offer is not available to monthly paid or complimentary subscribers - but you are welcome to upgrade to a Paid Annual Subscription

Upgrade to Annual Paid Subscriber

If you are already an Annual Paid Subscriber we will continue to honor your current lower annual subscription price when you automatically renew, but you will not receive the incentive package for new subscribers.

THE LIGHT DOCTOR newsletter by Dr. Martin Moore-Ede is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.

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