Circadian Light – Is it Reality or a Manifestation of Cognitive Bias?

The Lighting Industry suffers chronically from the ‘Law of the Instrument’ – a form of cognitive bias:

If the only tool you have is a hammer, it is tempting to treat everything as if it were a nail.

Abraham Maslow
To Illustrate

Five people enter a room; An Architect, a Banker, a Structural Engineer, a Lighting Designer, and the Building Owner.

“Without me this room would not exist in its current form” says the Architect.

“Without me, this room would never have been built, as I funded its construction” says the banker.

“Yes, but without me, the walls would not be standing and the roof over your heads would not be safe to walk under” says the Structural Engineer.

“Oh, but, without my lighting, you would not be able to see anything in this room, and its purpose would be lost” says the Lighting Designer.

The owner then pipes in. “Excuse me, but without my need, and my defined purpose for this space, it’s form and structure would not exist, your money would not be needed, and the lighting within would be irrelevant, so none of you fools would be standing here. Now get back to work!

The moral: We need to constantly remind ourselves that we do not live in singularity bubbles, we live in a larger holistic space, where many factors surround a larger definable reason for existence.

The Second Cognitive Bias – The Causal Determinism Fallacy

We often hear the statement that because man evolved in natural light, that the characteristic of natural light itself during human evolution establishes our circadian response behavior, and that natural light can be then used to determine the perfect cycle of light in support of circadian functionality.

This completely ignores that humans evolved on this planet from the farthest northern hemisphere to the the deepest southern hemisphere, where natural light spectral distribution, daily illuminance, and seasonal variability present a very wide range of lighting conditions – yet there is no indication that any one region has produced superior humans, founded on their evolution under some form of perfect light.

Further to this, the fallacy assumes also that human biology is a hard wired machine like system with no capacity to evolve, adjust, or accomodate variabilities, even within a selected region. We know this is not the case, as humans have proven capable of accomodating a wide range of lighting conditions around the world, 24 hours a day.

We also know, from other studies, that the circadian clock functions at a biological level on a 23.5hr to 25hr cycle, without any entrainment from light of any source involved – that light can trigger certain points within the cycle, but no necessarily change it once entrainment has been set.

One has to ignore thousands of years of demonstrated adaptation to lighting and environmental conditions in which human life has thrived, to believe that there is any such thing as a singular or generalized version of circadian function programmed into the hardwiring of humanity, based only on lighting conditions distant ancestors were exposed to. Individuals with deep roots in one region frequently move to another region with significantly different environmental conditions, and readily adapt to their new surroundings, so the effect does not seem applicable beyond conjecture.

Where Does Light Fall in the Spectrum of Circadian Influencing Factors?

Here are the primary functions effecting everyone’s sleep/wake cycle (in no specific order):

  • Age
  • Noise
  • Hearing disorder (tinnitus)
  • Genetic Predisposition
  • Alcohol Use
  • Physical Fitness
  • Health and Wellness Condition (known and unknown)
  • Stress and Stress Tolerance
  • Medicines taken
  • Illness (state of and type)
  • Mental Fitness
  • Sleep state health conditions (apnea, insomnia, etc.)
  • Diet
  • Weight
  • Blood Pressure
  • Blood Sugar level
  • Sugar and/or Caffeine consumption and tolerance
  • Individual Melatonin cycle timing and serum levels
  • Individual Hormone cycle timing and serum levels
  • Pre-sleep period activity or preparation
  • Waking state activities (first hour of waking)
  • Room temperature
  • Body temperature
  • Natural Light exposure
  • Artificial Light exposure

To Lighting People, the only factor that will be pointed to will be the nail of “Artificial Light exposure” upon which they can strike with their magic light hammer. For everyone else, it is obvious there are a myriad of issues involved. To this, the response is easy enough. “We can’t do anything about most of those factors, but we can do something with light!” Of course, this is exactly why the Law of the Instrument exists and applies here.

To this point, I suggest that if your job is a bore and does not engage you mentally, you are going to feel nappy after lunch, no matter how great the lighting is. If the light levels in your work spaces are too low and/or task physical space arrangement causing you to exert additional energy in seeing and cognition of visual tasks, you are going to feel fatigued as the day wears on, regardless of the SPD of the light itself and its “melatonin suppressive” content. If you are experiencing a monotonous, unchanging environment for long periods without a break, you are going to feel fatigued and nappy – lighting cannot fix that.

When you are on the beach feeling warm, relaxed, and allow yourself to succumb to the release of all thoughts – you may fall asleep, even if that blazing sun has your melatonin suppression machinery cranked up to 11.

If you have a job or family condition that keeps you wound up to the point it keeps your head spinning at night, you are not going to sleep well, even in pitch black silence. If you are over-weight or in poor physical condition, or eat a lot of sweets, drink caffeine late in the day, regardless of melatonin level, you are going to have problems falling to sleep, even if the lights are perfect. If you have Tinnitus that drives you nuts at night, you may not sleep without some form of external distracting noise, even if the lighting is off well before bed time. If your blood pressure is high, you suffer from arthritis, suffer from sleep apnea, have a genetic predisposition for insomnia, are over the age of 55, or feel too hot under the covers, you are going to suffer sleep disruptions – regardless of lighting conditions around you.

In other words, lighting is not a singularity. In a wide number of cases, it may even be irrelevant.

The Homeopathic Approach

In the real world, setting all other causes aside as being uncontrolled variables means that application of circadian light is nothing more than homeopathic in nature. If light is selected as the singularity in causing an ailment, then prescribing light in various mixes and levels will then be prescribed as the cure. That is the definition of homeopathy. It is not science, even if many of the tenants of the practice are founded on selected, lighting focused research results. I’d think we’d like to avoid going down this road, but it is pretty much where we are right now.

The Holistic Approach

The true solution to improving the sleep-wake health of humans is to consider all of the factors involved that impact how we feel from the first waking moment to the last, and everything in between. In this, the importance of each factor and its prioritization can be established.

Another design factor rarely discussed in detail, is the need to survey existing conditions, to expose whether light is a factor at all. In my article “Bedroom Lighting for that Restful Sleep” I surveyed my workplace and home spaces throughout the day to evaluate my circadian light exposures using known metrics at the time. In this, I found that my exposures were well under the maximums for rest, and a bit under in wakeful states. Most importantly, this survey was done in spaces that had minimal effort put into being circadian cycle friendly. Yet, I suffer insomnia, along with millions of others, and have spent decades trying to resolve that. A serious case of Tinnitus is not helping, compounded by a sweet tooth, etc….

The point is, prescribing light as some grand cure-all, savior of mankind from its evil artificial light demons, is nothing more than the cognitive bias of a community anxious to create value with its hammer – to grow revenue. Those truly engaged in improving the sleep-wake behavior of occupants of indoor and outdoor environments will look at a far broader set of factors and engage in more complete activities to the benefit of occupants. This includes involvement with physical conditions, the condition of those exposed, and the environments involved and how they impart a mental state – and yes, lighting.

Ethical Dilemmas and Questions

In scientific study, there exists a dilemma in which it is considered unethical to do any tests on a population that has not been informed and consented to being part of the study.

Applying light as a prescriptive solution to globally impart a physiological response from occupants of a given space or environment, with no informed formal consent is an unethical act. Period.

The dilemma comes in several forms.

  1. If it is the supposition that fiddling with SPD and light levels will impart a positive result (whose perspective?), with minimal or no risk to those unaffected – with no data to establish efficacy of the application (objective value), are we practicing snake oil salesmanship, or fraud – depending on how far guesswork and subjective information is stretched?
  2. If it is stated that an employer will benefit from enhanced wakefulness of employees, without their knowledge or consent – why can’t those same employers simply demand that all employees take other forms of mostly-harmless performance enhancing drugs for a similar effect, without the employee’s knowledge?
  3. If the lighting industry continues to sell lighting product that has been proven harmful in any way to occupants of artificially illuminated spaces, why can this not be used as a basis for widespread law suits against all producers of lighting products, on the basis of knowingly exposing users to harmful light? In other words, as soon as it is established objectively, that light with certain characteristics does no harm, then this must become the standard for all lighting produced going forward, from an ethical point of view – or that all lighting that fails to fit within limits carry a requirement of informed consent from occupants to accept the risk of exposure. This is a Pandora’s Box issue, where once we expose that lighting is doing harm, can it continue to be produced and delivered without correcting that, essentially nullifying the circadian light movement by making it the de-facto minimum standard?
  4. If we recognize that circadian function is a holistic issue involving a wide range of factors well outside lighting – can we allow the lighting industry to control the narrative, without informing the public that it is but one of many factors involved, and that each individual’s environmental conditions and response will vary? Further, if it is believed that circadian function is being negatively impacted and has become a national health issue, that involves factors beyond light, can we allow the lighting community to present itself as solution provider that detracts from the larger holistic factors involved?
  5. The moment we confirm, objectively, that any set of lighting conditions is causing harm, are we not obligated to stop producing such products or applying them? If so, why do we continue to see application of horrific glare bombs in street lighting, uncontrolled brightness diffuse lensed architectural lighting, application of glare filled “volumetric lighting” practices, a lack of task lighting application? Simple conclusion: The lighting industry has never been hobbled by either ethics or good lighting principles. From the days of gas lighting burning entire blocks to the ground and low pressure sodium street lights – to the blinding array of LED products today… revenue generation has been the modus operandi from day one. Ethic is not a universal high priority.

Are circadian lighting practices and related products of value? I would say yes, for one basic reason. We now recognize that the SPD of the light sources and the illumination levels employed in our artificially illuminated environments are in need of improvement. Any time we remove a hostile characteristic from the environment and replace it with a beneficial one, stress is reduced, wellness increases and feeling of well being improves. So, even if lighting plays a minor role in delivering a benefit, eliminating bad lighting characteristics will produce a significant benefit in the balance.

We also need to address the need for retinal illumination over just surface brightness. We need to address the SPD of sources and move away from content that can potentially disrupt the sleep wake cycles of those exposed. We need to redress how we illuminate tasks, what light is emitted from displays, and how we control the light around us. With LED technology, we can do these things, and are ethically bound to pursue applying it to address these issues to the best of our ability.

We also need to redress lighting from the perspective of who is controlling the narrative. The IES, the IALD, and the CIE all need to pull it together and take control of the dissemination of information. There should be a movement toward certifying products as “circadian neutral” in order to establish a baseline of do no harm, and fund research that looks at the holistics of sleep-wake behaviors and establish what role lighting actually plays in the larger scheme. We need to curb the current condition of manufacturers with vested interests in circadian light as a market advantage, controlling the narrative, in order to broaden the subject and focus to deploy improved lighting industry wide best practices. Standards and metrics that can be universally applied and reported need to be established and acted upon.

If the lighting industry as a whole fail to act on new information regarding the potential harm and risks of lighting characteristics that can cause potential harm and reduced healthfulness of those exposed, it loses credibility. We are approaching a turning point at which we move from simple slow reaction, to more serious culpability, if not outright liability for failing to respond.

However, if we jump through hoops based on fallacious logic, marketing driven over-statements, and cognitive bias – unnecessary time and money will be wasted and credibility will be lost.

Follow Up:
Les Kacev offered his point of view on this topic as a comment. However, as it is longer than the original article, I have compiled it as a .pdf document for those interested:

Author: kwillmorth

Photographer and Artist

3 thoughts on “Circadian Light – Is it Reality or a Manifestation of Cognitive Bias?”

  1. Kevin, well said! The use of circadian effective lighting as a marketing tool is both potentially dangerous if it has effects and snake oil if it does not. As it seems the effectiveness is dependent on a body’s light exposure and experienced throughout the day the effectiveness falls into the snake oil in most lighting circumstances, however in the situation of hospital, care home or other residential institution it can veer into the dangerous unless applied with care and due diligence.

    It worries me that the WELL standard demands degrees of melanopic effective lighting without the strong evidential bodies of work to ensure their requirements fall completely within the “do no harm” area.

    It is up to the lighting design profession to discuss and advise on this along with all other aspects of lighting on behalf of the end user as opposed to the lighting industry.

  2. Les offered a comprehensive statement of his view on this topic that I have compiled in .pdf format at the end of my article for those interested, including a link to his firm LEDMetric. I thank Les for the time he invested and appreciate his point of view.

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