The Case Against Blue Blockers
Seeing the world through rose-coloured sunglasses.
Over the last few years, blue light blocking glasses have found a niche within the health and wellness space. They have been born out of the increasing amount of blue-rich and infrared-dark artificial light we are being exposed to at night. This problem has become so nefarious that within the literature, this type of exposure has its own term; ALAN (artificial light at night). These types of exposures have unparalleled negative consequences on biological rhythms and homeostatic balance. Blue light blocking glasses present a relatively simple way to at least ameliorate some of the detrimental effects of these artificial light exposures at night.
Light signals are transduced physiologically by interactions with the plentiful chromophores present all throughout the body. From amino acids to water, our bodies are full of compounds that interact with incident and endogenously created light (biophotons). Of particular interest for this story are the family of molecules called opsins. Opsins are visual and non-visual photoreceptors capable of exerting system-wide regulatory effects. When bound to vitamin A (11-cis-retinol), these proteins become photosensitive. When this opsin-vitamin A complex is excited by a photon, it undergoes a conformational change (11-trans-retinol) where it is said to be in its active state of phototransduction.
In biology, the most well studied opsins are melanopsin, rhodopsin and neuropsin. These opsins are concentrated in the retina where visual transduction takes place1. Melanopsin has a peak absorption at about 480nm (blue) and is known most well known for communicating time-of-day information to the rest of the body via the suprachiasmatic nucleus (SCN). This is front-and-centre in circadian biology due to the powerful regulatory and photoentrainment effects of short-wavelength visible light.2
More and more information was accumulating in the early 2000’s suggesting that exposure to ALAN was disturbing circadian rhythms, suppressing melatonin release at night, and ultimately leading to poor sleep quality. As this trend continued and the understanding of melanopsin deepened, there was an increasing need for the ability to limit the short wavelength visible light into the retina where melanopsin is primarily concentrated in order to quash the negative impacts that light would have on circadian rhythms. Here is where the concept of tinted spectacles was conceived.
Blue blockers are still relatively new to the scene, with little research being done on them directly. While there are some studies that show positive effects on sleep quality, the theoretical beneficial effects of these tinted lenses appear to be both valid and crucial in our modern, blue-lit world3. One publication goes as far as to suggest that the wearing of blue blockers at appropriate times of the day could be protective against cancer, particularly those of the breast, prostate and ovary.4
Blue blocking glasses have become an important part of the toolkit of practitioners and lay people alike for combating the horrendous artificial light environments we are faced with everywhere we go. They present a relatively cheap and easily actionable medium with which to improve one’s health; something the countless blue blocking glasses companies continue to tout loudly to this day.
But like many things, marketers and central figures in the health and wellness space tend to omit nuance from their discussions and can easily fall prey to “The Bryan Johnson Fallacy” of thinking that what we know, is all there is to know. This has led to what I call “melanopsin tunnel vision”, and ultimately has obscured some of the subtleties of this complex circadian story. It seems as though the story and message of blue blockers lures users into a false sense of security.
The sensationalised story of melanopsin, artificial light and blue light blocking glasses has potentially obscured some of the subtleties of this complex circadian story of which we are still to gain any kind of deep appreciation for.
As previously mentioned, the increasing intrigue of melanopsin has led to its identification in many tissue types. It has been quantified in human keratinocytes, melanocytes and fibroblasts (skin cells), where it likely plays important roles in skin homeostasis as well as signaling for preconditioning and repair of light-induced damage that typically accumulates throughout the day. The problem is that the presence of melanopsin in the skin demonstrates that phototransduction does not exclusively occur via the retina.
This is a salient issue that cannot be addressed with blue light blocking glasses as ALAN can still reach the skin and disturb local (and probably global) biorhythms. The use of blue blockers, however, can perpetuate a false sense of security where some might feel as though they can stay out at night and be immune to the detrimental effects of narrowband artificial blue light. The nature of the light environment still matters whether one is wearing blue blockers or not.5 While blue blockers may protect perhaps the most important receptors in the eye, they do not prevent any untoward effects blue-rich artificial light is having on the skin (and by extension, the rest of the body). This is a problem that is rarely tackled in the health and wellness space and its resolution requires not only the limiting of short wavelength light at night, but also the restoration of our NIR/IR environment - hopefully in the form of DC incandescent bulbs6.
Another issue blue light blocking glasses create is that the lenses ultimately reduce the relative abundance of NIR/IR that can reach the eyes and balance the plentiful negative effects of short wavelength light. By using glasses of any kind (not just blue blockers) there is the potential of limiting other beneficial light from reaching the eyes. This is more relevant for those who use said times lenses during the day where NIR/IR-rich sunlight is available. Even in the presence of artificial light, the use of blue blockers could potentially be net-negative for health.7
The primary concern I have with blue light blocking glasses is that monochromatic light (of any colour) is an evolutionarily novel stimulus that can have highly variable inter-individual physiological effects. This notion is well understood in the field of syntonics where monochromatic light is used therapeutically.
Syntonics (also called colour therapy or syntonic therapy) is a discipline utilized in ophthalmology and psychology to help treat conditions ranting from learning disorders to trauma. Depending on the individual and the circumstances, different coloured lenses are used to shape the body's activities to promote specific responses - conceptually identical to using a nutritive supplement or drug. Broad spectrum light is being isolated just as one might extract curcumin from turmeric and then applied via the eyes to impart a physiological response.
In Jacob Liberman's classic book, “Light: Medicine of the Future”, there are astounding accounts of different patient's responses to different colour therapies. No individual responds identically to the same colour stimulus. One particular example in the book recalls one of Jacob's patients instantaneously being faced with a past trauma upon use of a pink syntonic lens. Canadian physicist, Anadi Martel's brilliant book, “Light Therapies” also covers the broad and inter-individual uses of colour therapies. Monochromatic light appears to have notable physiological and psychological effects that differ from person to person8. Some individuals may have beneficial and calming effects from green lenses, where others might experience the exact opposite.
The question then is, might the frequent use of the red/yellow tinted lenses in blue light blocking glasses have detrimental physiological and/or psychological consequences on some individuals? Might such lenses cause untoward effects on measures like heart rate variability, blood pressure, hormone balance, mineral balance and affect? This is a question that, despite a long history of colour therapy and its stark intra- and inter-individual responses, has scarcely been considered with the use of blue blockers.
Of course it goes without saying that our current LED and fluorescent lighting fixtures are also essentially monochromatic blue; the effects of which are broad ranging, devastating and relatively well known. John Ott’s “Exploring the Spectrum” documentary has a particular scene at approximately 48:13 clearly demonstrating the behavioural effects of different lighting fixtures.
All this is not to say that blue blockers should be avoided. However, careful and concerted efforts must be made prior to using blue blockers (particularly in children) to:
Evaluate the artificial light environment around you once the sun has set. Monochromatic or narrowband light is still evolutionarily novel and can have negative effects, even in the yellows and reds. We don’t exactly know what effects exposure to these types of light long-term could be.
Monitor subjective feelings of wellbeing when using blue light blocking glasses. It is probable that some people will not respond positively to having monochromatic red light coming into the eyes day in, day out. Everyone will respond differently to this stimulus, and while there are certainly benefits to be had by filtering short wavelength light at night, there may be more elegant solutions to circadian disruption in the modern world.
It is safe to say that there are many situations where blue blockers would almost certainly be a net positive in a horrendously blue-lit world. However, an ideal situation would be to not rely solely on red tinted lenses once the sun has set, but rather reintroduce broadband emitters of light that predominate in the NIR/IR, just like fire. Fire’s spectrum contains blues and greens, however, their relative abundance is so low compared to NIR/IR that fire tends to have a more positive effect on sleep onset and sleep quality. Mimicking fire light is our best bet for our homes where we spend most of our time at night. This could be done through the use of incandescent light bulbs if they were not illegal. One day (hopefully soon), this will change.9
Broadband light spectrums that predominate in the NIR/IR are the most physiologically benign. Any time we isolate and concentrate light, we are using it like a drug; in some circumstances it can be a medicine, but in others, a poison. Blue blockers are almost a necessary evil in the modern world, but sincere efforts must be made to understand the potential physiological and psychological effects of continued exposure to monochromatic red/yellow light.
Summary
Blue blockers have become very popular and meet some criteria for curtailing circadian disturbance. Evidence does suggest they could be helpful, but monochromatic light is far from evolutionarily consistent and at the end of the day, it is still alien light. We don’t know what we don’t know about potential untoward effects of blue light blocking lenses.
Photoreceptors like melanopsin are present in countless cell types including the skin. Blue light blocking glasses will not protect your skin from artificial light. Perhaps blocking artificial light through the eyes but not on the skin could generate even more detrimental health effects?
Syntonics is the study of colour on physiology and psychology. Each individual responds differently to various monochromatic light, making it likely that there will be people who have negative responses to the monochromatic light that comes through blue blockers. At the end of the day, blue light blocking glasses are syntonic therapy devices; wearing them will have therapeutic effects and it is unclear whether these effects could be positive or negative.
Lenses of any kind reduce the relative abundance of NIR/IR that can reach the eye, balancing out the visible wavelengths. In some circumstances (particularly use during the day) could be more damaging than helpful.
Ultimately, the problem is much greater than the presence of blue after sundown. Blue blockers can be extremely useful tools and many people benefit from using them. However, we cannot discount the notion that there will inevitably be individuals who do not tolerate monochromatic red/yellow light well at all; potentially to the point where their use is a net negative for health. There needs to be a more concerted effort to restore broadband emission that predominates the in the NIR/IR so that we can live in surroundings that do not require the use of such lenses.
Other relevant reading:
While these opsins are concentrated in the retina, they are distributed widely throughout the body and are found in ‘unconventional’ locations. Essentially everywhere that is checked, opsins are found. This goes against the original thinking that the opsin proteins were limited to visual transduction, thus, being constrained to the retina. As it turns out, melanopsin, the blue sensor is found in many other biological tissues.
Short-wavelength visible light has an incredibly powerful influence on biological rhythms because of the unrelenting reliability of day-night cycles throughout our evolutionary history. Earth’s light-dark cycles have been so reliable and unchanging that we have cemented them as the foundation upon which biology functions. Blue light is only available in nature at specific times of the day where the sun is out. Once the sun had set, very few (if any) blue wavelengths are available. Even moonlight, fire and lightning strikes are all predominantly infrared light, making the relative abundance of blue miniscule. Blue, and importantly, its absence thus provided a foolproof (almost) mechanism for curating and synchronizing physiological activities.
Some interesting publications on blue blockers include, “Amber lenses to block blue light and improve sleep: a randomized trial”, “Interventions to reduce short-wavelength ("blue") light exposure at night and their effects on sleep: A systematic review and meta-analysis”, and “Blocking nocturnal blue light for insomnia: A randomized controlled trial”.
Breast cancer appears to be one of the most sensitive to circadian disruption by artificial light at night. There is a great deal of evidence, both epidemiological and mechanistic to support the idea that ALAN causes breast cancer. This played out relatively recently in Denmark where women who developed breast cancer following their taking up of night-shift work were financially compensated for the medical damages. Cases such as this one are real-world examples of just how damaging our detachment from natural day-night cycles has become.
This effect has been demonstrated previously with experiments looking at photoentrainment by exposure of the back of the knee with artificial light. This should not be all that surprising as we evolved to have little-to-no light exposure at night through the eyes of skin, making exquisite sensitivity to even low lux artificial light plausible. It is also will known that sleeping with even very limited ambient lighting from devices of rouge street light can have notable health consequences. Also, while I have no evidence for this claim, I am almost positive blind individuals can influence their circadian rhythms by being exposed to light even without retinas. As it is assumed this cannot be, there is unfortunately no research I could find even postulating this question.
Direct current is stressed here as the flicker effect is underappreciated and is a salient part of why modern lighting is so damaging to health. DC converters eliminate this issue.
This is a trend I have seen quite a lot in the health and wellness space that I feel needs to be limited. The use of these glasses during the day is much less likely to be of benefit as they limit both blue and NIR/IR; both vitality important during the day. A circumstance where yellow lenses might be net-beneficial is during a short trip into a shopping centre where you will be able to avoid the assault of narrowband blue and then take them off when you get back outside. Long periods of time during the day wearing blue blockers could likely be doing more to disrupt your circadian rhythm than not.
I strongly suspect that markers of autonomic balance can be greatly impacted by exposure through the eyes by monochromatic light. This is precisely at the core of syntonics and cold therapies. This could theoretically be measured through heart rate variability, blood pressure, mineral balance, hormones and subjective reporting.
On a positive note, I have personally been contacted by a diplomat of a European nation about trying to fix their country’s light problem. They were genuinely concerned about the health impacts of current lighting fixtures and is seriously building a case to present his parliament to reinstate incandescent lighting. This is a massive step in the right direction. I suspect this will be at least 20 years in the making before things really start to change.
Thank you, Cameron, for the VERY thoughtful highlighting of the important nuances!