Registered designer and wellness consultant DEBORAH BURNETT examines the body of knowledge related to electric light and human wellbeing and urges a cautionary approach to SSL touted to deliver health benefits.
A recent State of the Industry report issued by an Illuminating Engineering Society (IES) industry partner, the American Society of Interior Designers (ASID), identified six macro trends impacting the built environment. Among the six were technology, sustainability, and urbanization - small blips on the scale as compared to the number-one-rated $3.4 trillion/year industry now extending its influence into the built environment: health and wellbeing. This macro trend outranked all others by a third and demonstrated a strong rising interest in providing wellness-focused design solutions based on scientific discovery. This same trend is also gaining momentum within the lighting industry, as evidenced by the proliferation of bio-based color-tuned and blue-weighted lighting products touting numerous health benefits.
In the past, specifying lighting for built environments, streetscapes, and roadways was a job for engineering and design professionals whose only constraints have been the depth of the client's pocketbook shoehorned between energy code compliance and the project's creative and construction limitations. With the current growing body of scientific evidence in support of the premise that all light sources including daylighting and general lighting systems contribute to occupant health and wellbeing by impacting biological, physiological, and metabolic processes, the A/E/D (architecture, engineering, and design) communities must now face a new constraint - that of bio-ethical responsibility - to ensure that our lighting solutions will not only deliver lighting suitable for visual acuity but also provide lighting specifications that are not hindered with the potential for unintentional biological harm.
FIG. 1. Ambient light is critical both to our visual system and the circadian system, which impacts our basic life functions including genetic expression, neurochemical response, and even how well we sleep at night.
Since the 1950s when the term "circadian" was first coined by researcher Franz Halberg, research teams worldwide have been actively exploring the biological connection between ambient light and various human physiological systems, neuroendocrine functions, genetic expression, and even behavioral response.
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Based upon the groundbreaking work of researchers George Brainard and Russel Foster in the later part of the last century, the 2002 discovery of a unique set of cells located in human eyes, called the intrinsically photosensitive retinal ganglion cells (ipRGCs), opened the door for further research exploring how electrically provided light may also impact the same biological, genetic, metabolic, and behavioral response as do naturally provided periods of light and dark. For more background, see an interview published in LEDs Magazine last year.
Subsequent scientific and medical studies concluded that yes, electrically provided light, especially when provided during the naturally darkened photoperiod, will impact circadian systems of all living life forms. On the flip side, ongoing research is also demonstrating the connection of electric light to diseases such as breast cancer, diabetes, metabolic syndrome, and a host of other health-related conditions exacerbated, or in some cases, initiated and promoted by building occupant exposure to bright, so-called "blue-rich" light at the wrong time within a 24-hour photoperiod.
The emerging problem was of such grave concern that in 2012 the American Medical Association (AMA) changed its policy (H-135.937) and issued a stern caution against the use of blue-rich white light sources at night - the reason being that not only was the potential for disease increased but also the discovery of the role this type of light plays in a serious health malfunction called circadian desynchronization.
The human circadian system can be thought of as a master gatekeeper, or centrally located master cog in a complex interlocking system of genes, hormones, and neurotransmitters that orchestrate the functionality of our cells, most genes, and all biological processes, thus powering a totally integrated organism (Fig. 1). In humans, the circadian system is designed as a biological anticipatory system comprising molecular networks charged with keeping a person attentive, sufficiently rested, and actively healthy by aligning and adapting the biology to the environment. It does this by readying the body and brain for the next process by using ambient light signals as a timing cue. The purpose for the interconnectivity between environment and biology is an evolutionary need to increase survival odds and ensure viable reproduction. But humans are not the only beings endowed with a circadian system, as all life forms possess a similar system: Even the recently discovered rudimentary 540-million-year-old hydra possessed this invaluable survival component.
Today, man has an advanced circadian system that depends on environmental ambient cues, such as the Earth's 24-hour photoperiods, to realign the innate 24.2-hour (approximate) circadian rhythm and initiate the process of sleep so the act of sleep can happen at night. Combined, the circadian rhythm, inverse to the sleep/wake cycles, drives all of our physiological and metabolic processes, biological functions, neuroendocrine activity, and genetic expression to keep us healthy and active. Important life-sustaining functions under circadian system influence include heart rate, blood pressure, immune system function, wound healing, hunger, satiation, and even urine output. With all of this at stake, one can only begin to realize the grave concern a desynchronized circadian system would pose; and, as scientific discovery is now reinforcing, electric light has the potential to do this with the flip of a switch.
Lighting as new pathway to health?
Translated to the practice of lighting design, the connection between electric light and biology initiated tremendous marketing potential for applications where decreasing occupant fatigue, improving patient outcomes, and increasing performance on standardized tests sparked worldwide efforts to capitalize on the wellness benefit. Initial products and accompanying health claims touted exceptionally high levels of blue-rich white light and so-called circadian lighting products for one-size-fits-all application in 24/7 operations, high-performance office environments, call centers, and patient hospital rooms. From color-tuning LED lighting systems to artificial skies, the idea of making building occupants healthier and more productive by employing lighting products that mimic daylighting color shifts throughout the day has created an entirely new and potentially huge market for premium lighting products throughout the world.
Opportunistic early movers
Linking light to wellness has also encouraged design practitioners and manufacturers to promise benefits beyond visual acuity by citing claims of increased productivity, enhanced sleep, and reduced error rates - all the while not fully cognizant as to the physiological processes that are thought to be responsible for these benefits (Fig. 2). The catch-phrase human-centric lighting (HCL) is becoming increasingly common throughout the industry, from individual consultants in the retrofit industry to one of the world's largest manufacturers of lighting and electrical products - but what specific credentialing is required to make these claims of providing advanced expertise and health benefits from architectural lighting sources?
FIG. 2. The scientific community continues to explore the non-visual response to light, but research shows several factors composing the quality of light exposure that either enhance or disrupt our overall health and wellbeing, in worst cases, causing severe maladies such as cancer.
As a rule, lighting and design practitioners stay within defined practice realms and question stakeholders to discover solutions. But with the link between light and health, there are no time-honored rules, an established body of knowledge, or proven best practices that can be used to redefine this paradigm of lighting design with health benefits. Most of us don't even know what we don't know, so how can we begin to understand - let alone apply - what scientists are still discovering?
The fact remains that even scientists don't know all the answers yet, but what they do understand is compelling. For many researchers, it is commonly accepted that if lighting products sold and design solutions provided are nothing more than color-changing lights based on current exterior conditions - without consideration for those components of natural light that do impact biology such as light intensity, timing, location, motion, and spectral distribution percentages - the resulting design solutions are missing the real issue and pose potential health risks to unsuspecting building occupants.
In my opinion, installing such projects based on unsupported claims - and without obtaining occupant consent and education as to the potential benefits and possible risks associated with blue-weighted electric light - may in some cases open the designer and manufacturer to charges of unethical use of human subjects and, at the very worst, inflict or exasperate occupant desynchronization simply because of a designer's false assumption or wrong guess during the spectral power distribution (SPD) specification and commissioning process. To me, that is a poor man's version of practicing medicine without a license.
Just the facts
So, as one design professional to another, the first question to ask should be what do we know as scientific fact, then how can we explain it to our clients? I like to explain the complex link between light and health with a simplistic approach: describing the human circadian system functions like an internal see-saw comprising the circadian rhythm and sleep/wake cycles, which function in a yin-yang manner, generating biological energy in a reciprocal fashion. In other words, when one biological function or process is optimized, another is dormant; all the while the neurochemical response generated between these two periods offers the "life force" to keep us alive, happy. and healthy.
A prime example of biological reciprocity is the current understanding of the tradeoff between the turning on and off (expression and silencing) of each neurochemical and circadian gene. The most studied at this point is the hormone melatonin. Simply put, exposure to critically timed blue-rich white light during the daylight hours is necessary to suppress melatonin, which in turn ensures ample melatonin supply for nighttime release because darkness at night is vital to express or produce this hormone in normal amounts. Health problems and circadian desynchronization arise when blue-rich white light exposure happens at night and the release of melatonin, a critically important tumor suppressant and DNA protectant, is hampered or in some cases delayed by several hours - thus setting up conditions of ill health ranging from cancer to migraine headaches, increased depression symptoms, and even weight gain. Keep in mind, however, that this model is unique for each species and varies among individuals dependent upon several factors; chronological age and the presence of neurodegenerative disease seem to be the most notable.
Opportunists will not get it
Both the scientific and medical community are now coming to realize that a potential problem arises when circadian-naïve design professionals are unintentionally setting into motion the very basis for circadian desynchronization by blindly specifying blue-weighted white light for most projects irrespective of biologically appropriate seasonality, circadian-correct time of day or night, or even under certain conditions contraindicated for specific age groups. These include teens and the elderly, who need a delayed morning exposure to bright light, versus adults and grade schoolers. After all, what happens if we specify these products and the assumptions we use to apply what we think are wellness-directed light protocols and they prove to be wrong?
Consider the case of a lighting manufacturer who mocked up a healthcare lighting project that provided exceptionally high light levels for bedridden patients in an intensive care unit (ICU). It is widely believed that light aligns circadian rhythms and maintaining the patient's circadian rhythm improves patient health and expedites recovery, so why not boost light levels with concentrated short-wavelength electric light directly above patient heads? Not so fast... Lacking the proper science, medical research, and a general knowledge of typical ICU patient conditions and the pharmaceuticals they receive, the manufacturer failed to note that ICU patients often receive a combination of 250 commonly prescribed phototoxic drugs. A last-minute observation by a peer reviewer prevented a disaster. But will the average lighting designer be so lucky when asked to design the next senior living facility, hospital neonatal ICU, or 24/7 factory filled with hundreds of shift workers unknowingly suffering from a newly recognized sleep disorder called shift work sleep disorder (SWSD)?
Addressing that issue, the International Commission on Illumination (CIE) recently issued a statement citing that lighting professionals are a long way from being able to apply viable wellness lighting products to achieve specific health benefits for each occupant of every building. The CIE stated, "The missing understanding of the input-output characteristics between light stimulus and the resulting non-visual response seems to make tailored light application for a desired lighting effect impossible."
This calls to mind a principle from bioethics, which opines that given an existing problem it may be better not to do something, or even to do nothing, than to risk causing more harm than good. However, this was not the case 30 years ago when lighting manufacturers rushed to conclusions with the introduction and promotion of so-called full spectrum lighting. Such was the case in 1985, when after many claims promoting health benefits that could not be validated except by industry-sponsored papers of questionable scientific value, the US Food and Drug Administration was forced to instruct the worst offenders to cease and desist from claiming any health benefits from the use of their lighting products. Could we be at this same point today?
With the advent of tunable LED-based products now capable of delivering both positive and deleterious circadian system impacts, will history repeat itself as we tread surreptitiously into the sandbox of uncharted quasimedical practice? Given what we know tempered with the concerns of the CIE, AMA, and World Health Organization, and coupled with an accelerated scientific discovery trajectory, two very important questions need to be raised: 1) Would it not be wise for lighting manufacturers and HCL advocates to curb back promises of improved cognition, enhanced sleep, and reduced fatigue attributed to simple installation of color-changing or enhanced-high-CCT lights? 2) How do we with clear conscience continue to explain our industry-wide failure to advise - let alone warn - stakeholders and occupants as to the potential for both great benefit and potential harm from the lighting products we currently sell and specify?
We don't yet know what the future holds, but all indications are that the lighting industry will continue to push dangerously into medical sandboxes simply because there is too much money at stake. So to protect ourselves from liability and our profession from practice restraining orders, we had better wake up and become proactive by demanding scientifically-vetted (not industry-sponsored) application guidelines, and specifier educational requirements for circadian-system basic knowledge. But the most important thing we can do is for each of us to personally embrace the fact that promoting health benefits by installing tunable LEDs without proper protocols and occupant educational guidelines is nothing more than color-changing snake oil capable of delivering unintentional harm.
DEBORAH BURNETT, ASID, AASM, is a principal and partner in Benya Burnett Consultancy (benyaburnett.com).
Human-centric lighting and the effects of lighting design on human wellbeing are key topics during the Smart Lighting Track taking place on Mar. 3, 2016 at Strategies in Light. Register for the event, co-located with The LED Show, and participate in the discussion.