Seeing the Light: The Problem of Modern Lighting
Modern lighting has generally been presented as an engineering success. LEDs produce more visible light from less electricity, last much longer than incandescent bulbs and generate less waste heat. From the standpoint of energy efficiency, the transition seems an obvious improvement. But a long essay by A Midwestern Doctor (link below), raises a different question: what if efficiency measured in lumens per watt is not the same thing as biological suitability?
Human beings evolved under sunlight, which contains a broad range of wavelengths. These include ultraviolet radiation, visible light and substantial amounts of infrared radiation. Modern artificial lighting produces a very different spectrum. The argument developed by A Midwestern Doctor is that replacing natural light with a relatively narrow artificial spectrum, particularly when combined with spending most of our lives indoors, may have biological consequences that conventional lighting policy has insufficiently considered.
There are several different levels to this argument, and they should not be confused. The effects of light upon circadian rhythms and sleep are well established. There is also substantial research into photobiomodulation and the biological effects of red and near-infrared light. More controversial are claims concerning cellular optical communication and so-called biophotons. The latter remain scientifically disputed and should not be treated as established merely because some intriguing experimental findings exist.
The strongest part of the case begins with sunlight itself. Sunlight is not simply a mechanism through which the body manufactures vitamin D. Observational studies have reported associations between greater sunlight exposure and various health outcomes, including cardiovascular and overall mortality. One frequently cited Swedish cohort followed women for approximately twenty years and found higher mortality among those who avoided sun exposure than among those with greater exposure.
Such findings require caution. Observational associations cannot by themselves establish that sunlight caused the better outcomes, because people who spend more time outdoors may differ in many other ways. Nevertheless, the research complicates the once-common public-health message that sunlight should principally be regarded as something from which people need protection.
Ultraviolet radiation unquestionably contributes to skin cancers, and excessive exposure can be harmful. But complete avoidance of sunlight has its own potential costs. UVA exposure, for example, can stimulate the release of nitric oxide compounds in the skin and temporarily reduce blood pressure. Bright daytime light also helps regulate circadian rhythms, while appropriately timed light exposure has long been used in treating seasonal affective disorder. The reasonable conclusion is therefore neither that sunlight is harmless nor that it is a toxin. Human biology evolved in an environment containing daylight during the day and darkness at night, and modern indoor life has altered both sides of that relationship.
Artificial lighting differs from sunlight not only in intensity but also in spectral composition. Traditional incandescent bulbs produce light by heating a filament. Their spectrum is relatively continuous and contains substantial red and infrared radiation. Much of that energy was classified as inefficient because it does not contribute greatly to visible illumination. White LEDs operate differently. Many use a blue LED combined with phosphors that convert part of the blue light into longer visible wavelengths. The resulting light can appear white to the human eye while possessing a spectral distribution quite unlike either sunlight or incandescent light.
The eye is not merely a camera. Light reaching the retina helps regulate biological timing. Melanopsin-containing retinal cells are particularly responsive to shorter-wavelength light and play an important role in controlling the circadian system. Blue-enriched light during daytime is therefore not inherently bad; daylight itself contains plenty of blue light. The problem arises principally from timing. Bright, blue-rich light late in the evening can signal to the brain that it is still daytime and delay normal circadian processes associated with sleep.
The modern environment often gives us almost the reverse of what human biology historically encountered. Many people receive relatively little bright natural light during the morning and daytime because they work indoors, and then expose themselves to artificial lighting, televisions, computers and phones well into the evening. We have, in effect, comparatively dim days and comparatively bright nights. That is a significant change in the human light environment, and one does not need controversial theories about cellular communication to regard it as biologically important. Sleep, mood, hormone secretion and metabolic processes are all influenced by circadian timing.
Infrared radiation raises another interesting issue. Because infrared contributes relatively little to human vision, conventional measures of lighting efficiency tend to treat much of it as wasted energy. Yet red and near-infrared wavelengths can interact with biological tissues, and photobiomodulation has become a substantial area of research. There is evidence that particular wavelengths of red and near-infrared light can influence mitochondrial and cellular processes under certain conditions. That does not establish that ordinary LED lighting causes disease because it lacks infrared, but it does challenge the assumption that invisible wavelengths are necessarily biologically irrelevant.
The question is therefore worth asking: if we design artificial illumination solely according to what the human eye perceives and how little electricity is required to produce it, are we overlooking biological functions of wavelengths that contribute little to vision?
Flicker provides another concern. Depending upon their electronic drivers, some LED lamps fluctuate rapidly in brightness. The flicker may be too rapid to be consciously perceived while still potentially producing visual discomfort, headaches or other symptoms in susceptible people. The quality of LED products varies greatly, so it is misleading to treat every LED lamp as biologically identical.
A Midwestern Doctor's essay also revisits the unusual work of John Ott, who became interested in how different forms of artificial lighting affected plants and animals. Some of Ott's experiments and interpretations remain controversial, and they should not be treated as definitive demonstrations of the health effects of modern lighting. Nevertheless, the general proposition that biological systems can respond differently to different wavelengths of light is hardly controversial today.
The most speculative part of the story concerns biophotons and the earlier concept of "mitogenetic radiation." In the 1920s, Alexander Gurwitsch reported that dividing cells emitted extremely weak ultraviolet radiation that could influence cell division in neighbouring tissues. The phenomenon became the subject of considerable research before largely disappearing from mainstream biology. Later advances in sensitive photon detection demonstrated that living tissues can indeed produce extremely weak photon emissions, now commonly described as ultra-weak photon emission or biophoton emission.
What remains uncertain is what these emissions actually do. The existence of ultra-weak biological light does not by itself demonstrate that cells possess an important optical communication network. Still less does it demonstrate that modern artificial lighting disrupts such communication and thereby produces disease. Those are much stronger propositions requiring much stronger evidence.
Nevertheless, the history is scientifically interesting. Biological systems generate weak electromagnetic emissions, and the possibility that some of these emissions have biological functions remains a legitimate subject for investigation. Gurwitsch's work should therefore be neither accepted uncritically nor dismissed merely because it belongs to an unfashionable chapter in the history of biology.
Windows and spectacles introduce another difference between outdoor and indoor light environments. Ordinary window glass blocks much ultraviolet radiation, while specialised coatings can modify other parts of the spectrum. Spectacle lenses similarly alter the wavelengths reaching the eye according to their materials and coatings. This does not establish the stronger claim that wearing glasses or living behind windows causes disease. It simply reinforces the broader point that indoor illumination is not spectrally identical to being outdoors.
The practical conclusions from all this are remarkably modest. Obtain adequate outdoor light during the morning and daytime. Avoid staring directly at the sun, and use appropriate sun protection when exposure is intense or prolonged, but do not assume that spending almost every waking hour indoors is biologically neutral. At night, reduce unnecessary bright lighting. Warmer and dimmer illumination in the hours before sleep is more compatible with normal circadian signalling than bright, blue-rich light. Screens can be dimmed or shifted towards warmer colour temperatures, although reducing their use before bedtime is simpler still.
When choosing LEDs, colour temperature and flicker performance deserve consideration alongside energy efficiency. Warm-white lamps are generally more suitable for evening living spaces than high-colour-temperature lamps intended to resemble daylight. High colour-rendering quality can also produce more pleasant illumination. Incandescent and halogen lamps provide a broader, warmer spectrum and substantial infrared output, although they consume considerably more electricity and are increasingly restricted or unavailable in some jurisdictions. Whether their biological characteristics provide meaningful health advantages over good-quality LEDs remains a question requiring better research rather than confident declarations on either side.
The larger issue raised by A Midwestern Doctor is nevertheless worth considering. Lighting policy has largely defined progress through energy efficiency, cost and longevity. Those are important considerations, but they are not necessarily the only ones. Light is an environmental signal to which living organisms respond. Humans evolved under bright, spectrally broad daylight followed by genuinely dark nights. Modern life increasingly provides something quite different: comparatively weak indoor illumination throughout the day followed by artificial light extending deep into the night.
That mismatch is real even if some of the more ambitious theories about infrared radiation and cellular optical communication eventually prove incorrect. The sensible response is therefore not to declare LEDs poisonous or to imagine that every forgotten experiment has overturned modern biology. It is to recognise that lighting is a biological exposure as well as an engineering technology.
Energy efficiency asks how much visible light we can obtain from a watt of electricity. Biology asks what that light does to the organism exposed to it. Modern lighting policy has become very good at answering the first question, but it may be time to pay considerably more attention to the second.
https://www.midwesterndoctor.com/p/the-hidden-harms-of-modern-lighting
