Light is the brightness that comes from the sun, fire, electrical devices, etc. that allows things to be seen.
Light is a form of energy that travels in waves.
Color is the way our brain interprets different wavelengths of visible light. In visible light, wavelengths range from 380nm (violet) to 760nm (red).
When light hits an object some wavelengths are absorbed, and others are reflected. The light that is reflected is the color that we see.
Humans can see light with wavelengths between 400-700 nanometers. This is known as the visible light spectrum, which is a subset of the full electromagnetic spectrum.
Natural light is produced by the sun, and it contains all the colors of the visible light spectrum.
The key properties of light include:
Intensity – which corresponds to the number of photons emitted each second, also known as brightness.
Color – refers to the wavelength of the emitted photons.
Saturation or “chroma” – refers to the purity of a color.
Color Temperature – is meant to characterize the tint of color (being warmer or cooler).
Coherence – refers to the degree of synchronization to be found in the waves of the multitude of photons comprising the light. (Anadi Martel)
Polarization – refers to the orientation of the electric and magnetic fields that make up light. The orientation can be linear or circular. A common example of this is polarized sunglasses that filter out light with horizontally oriented polarization.
Artificial light sources can include incandescent bulbs, halogen bulbs, fluorescent bulbs, sodium-vapor lamp (typical street lights) and light-emitting diodes (LEDs). These do not radiate a full spectrum of colors; some produce warmer light than others.
Light produces different hues, which are differentiated by being “warm” or “cool”. Color temperature describes the appearance of light to the human eye relative to the “warmth” or “coolness” of white light, and it’s measured in Kelvin (K). Contrast to how you typically think of temperature, the lower the color temperature, the warmer the light; the higher the color temperature, the cooler the light.
Cool lights (about 5500K – 10,000K) have an unmistakable blueish tint that ranges in temperature from “cloudy sky” looking to “clear blue sky”. These cooler temperatures are equivalent to the sunlight temperature outside during the day. So, while they may be pretty for home and office interior designs, these lights can seriously throw off your circadian rhythm during the evening time if your eyes are interpreting that it is in fact daytime.
Cool white lighting (4000K – 5500K) is often used by major retail stores, white-collar offices and other institutions because it’s associated with promoting alertness and productivity.
Warmer lighting (1000K – 4000k) is arguably the healthiest lighting for humans to absorb because it emits the least amount of (artificial) blue wavelengths of light. A candle is 1800k and a typical old-fashioned incandescent tungsten bulb is 3200k.
Most of the light around you is invisible. This is because the eye is only able to see light at certain wavelengths.
There are 3 biological pathways of light:
Vision – eyes are incredibly sensitive to changes in light, and vision is the sense that transmits the most information to the brain.
The Nonvisual Optic Pathway – also known as the “energetic circuit”, allows light to directly influence the hypothalamus and regulate the secretions that come from the pituitary and pineal glands (e.g. melatonin at night time).
Photobiomodulation – increases production of ATP (energy) in the mitochondria of the body’s cells; it’s like photosynthesis for the human body.
The history behind using light for healing.
“Heliotherapy” is known as the therapeutic application of sunlight to treat health conditions. It’s one of the most ancient therapeutic measures employed by humans, and it’s believed that the ancient Greeks were the first people to use this method.
The name heliotherapy is derived from two Greek words: Helios, meaning the sun, and therapeia, meaning healing power. Hippocrates (460 B. C.), “the Father of Medicine,” used sunlight in treating tuberculosis. In fact, he used what appears to be a very modern treatment for this disease, since he recommended that the sufferer be sent away to the hills beyond the city, where he would have plenty of rest, fresh air and sunshine. (CHEST Journal)
In 1903, Niels Finsen received a Nobel Prize in Medicine for his work on light therapy (also known as phototherapy at the time). His work showed that certain wavelengths of light had beneficial effects for the treatment of Tuberculosis.
Phototherapy has also proven to be effective in the fields of dermatology, neurology and physiotherapy.
Auguste Rollier was a Swiss physician who devised a technique for exposing the body to sunlight to heal certain ailments. His clinic, called “Les Frenes”, was the first large, purpose-built sunlight therapy facility to be constructed in the world. (Michael Hamblin)
In contrast to heliotherapy, which is the therapeutic use of sunlight, photobiology is the therapeutic use of artificial light to improve one’s health.
In Europe during the 1960s, scientists found that specific wavelengths of light had therapeutic effects on tissues of the body through a process called photostimulation. This process uses light to artificially activate biological compounds, cells, tissues, or even whole organisms. One example of using this process is “light-treating” babies for jaundice, a relatively common condition of newborns.
Low Level Laser Therapy (LLLT) sometimes known as Low Level Light Therapy or Photobiomodulation (PBM) is a low intensity light therapy.
LLLT utilizes non-ionizing light sources, including lasers, light emitting diodes, and/or broadband light, in the visible (400 – 700 nm) and near-infrared (700 – 1100 nm) electromagnetic spectrum.
In the early 2000s, NASA started to use LED light therapy technology for muscle regeneration. The studies conducted at this time were significant because they showed that the use of LED light therapy could stimulate and essentially boost the primary energy processes in the mitochondria of every single cell in the body.
Each color has a different wavelength of light (measured in nanometers). When applied, each wavelength can have a chemically different effect on your skin, muscles and bones.
The longer the wavelength, the deeper the light will penetrate your skin. Note: deeper penetration doesn’t necessarily mean that it’s the most appropriate wavelength for healing your specific condition. Everyone’s skin type is different, and some wavelengths are more appropriate for healing muscles rather than skin.
A common misconception, and the main reason why LLLT technology hasn’t seen more widespread adoption, is that people have for a long time thought that it was only accessible in doctors’ offices, where these treatments would often cost thousands of dollars.
There are now many light therapy devices on the market, and a wide variety of suggested doses for different wavelengths of light. This has caused quite a bit of confusion in the medical field, and has made it more difficult for physicians and medical practitioners to decipher which doses and devices are actually the best for their patients.
There are now many clinics that do skincare treatments with red and near-infrared light panels for about $50-$300 per session. But research shows that at-home light therapy devices can be just as effective for people to use — at a fraction of the cost! This means that once you purchase your own device for a couple hundred dollars, you can do unlimited sessions at home, at your convenience, basically for free.
“Most of the early work in this field was carried out with various kinds of lasers, and it was thought that laser light had some special characteristics not possessed by light from other light sources such as sunlight, fluorescent or incandescent lamps and now LEDs. However, all of the studies that have been done comparing lasers to equivalent light sources with similar wavelength and power density of their emission, have found essentially no difference between them.” (Michael Hamblin, PhD.)
Tools of light medicine include:
Lasers – which can generate light with very precise wavelengths.
Intense Pulsed Light – These lights emit several powerful pulses per second and are frequently used in dermatology and aesthetic medicine.
LEDs – Can be used instead of lasers, they come in a variety of strengths and wavelengths for different purposes.
Fluorescent lamps – Mostly used in the treatment of depression and for other chronobiological applications. (Anadi Martel)
Light’s Influence on Health
“When trace amounts of certain wavelengths of light are missing from your “light diet”, this can have a staggering effect on your health.” – John Ott
Specific types of light have a profound impact on our health, and are actually necessary nutrients, similar to the nutrients found in food. (Ari Whitten)
Certain wavelengths of light can help power up our cells, affect hormones and neurotransmitters, balance our mood, enhance physical performance, hasten recovery from stress, increase alertness, improve sleep, and positively affect the expression of our genes. (Ari Whitten)
Different colors of light penetrate skin with different intensities. Those light waves stimulate cell activity.
Photobiomodulation allows oxygen into the mitochondria and prevents nitric oxide from halting energy production.
There are two key mechanisms of how red and near-infrared light therapy benefits cellular function and overall health:
Stimulating ATP production in the mitochondria
Hormesis – the process of building up the anti-inflammatory, anti-oxidant and cell defense systems of the cell
Photobiomodulation has been shown to increase muscle strength, especially when used in conjunction with strength training. Olympic athletes use light therapy to speed up post-exercise recovery and healing.
A 2010 study found that photobiomodulation helped 38% of study participants reduce their hypothyroid medication dose, and 17% of them were able to stop taking the medication altogether. (Ari Whitten)
While a low dosage of light may be ineffective, too high a dosage will not necessarily be better. An excess of light can actually inhibit the process that we are trying to stimulate.
Blue wavelengths (460-490nm) especially influences the different hormonal processes that govern our natural circadian cycle, including the secretion of melatonin, the key hormone that helps regulate the quantity and quality of your sleep.
“Another interesting thing [is] that throughout human history, people have liked to sit around fires … [E]very evening people would sit around a fire and expose themselves to infrared, a lot of it far-infrared. That’s [what] you get from glowing embers. It’s only in the last 30 years that people have stopped sitting around fires regularly … You could say Western civilization is suffering from a deficit of far-infrared light.” – Michael Hamblin (Dr. Mercola)
A recent study investigated whether patients with mild to moderately severe dementia or possible Alzheimer’s disease would improve when treated with near-infrared photobiomodulation (PBM) therapy. The patients were treated with near-infrared (NIR) light at 810 nm wavelength pulsed at 10 Hz, during a “12-week, Active-Treatment Period.” Results showed significant improvement in cognition, functional abilities for daily living.
Red Light Therapy
Red and near-infrared light are part of the electromagnetic spectrum, and more specifically, part of the spectrum of light emitted by the sun (and fire light). These wavelengths of light are “bioactive” in humans. That means that these types of light literally affect the function of our cells. (Ari Whitten)
When red light wavelengths are used on the skin’s surface, they can penetrate 8-10 millimeters into the skin.
While varying wavelengths affect the body differently, the most effective wavelengths for red light therapy and healing range from 625nm-900nm. (The TrueLight light therapy product line concentrates speciﬁcally on 630nm, 660nm, and 850nm wavelengths.)
Scientists have performed thousands of studies on the power of red and near-infrared light to enhance human health; and yet, most people have no idea that light therapy exists, let alone that it can be used to:
speed up muscle recovery and wound healing
increase strength and endurance
combat autoimmune and neurological diseases
reduce fine lines, wrinkles, and scarring of the skin
aid depression and anxiety
lose weight and fat
optimize brain function and mood
Red is the most commonly used type of LED light therapy. It helps energize the mitochondria in the body’s cells, which subsequently quickens tissue recovery and tissue rejuvenation by increasing blood flow and collagen stimulation.
By increasing blood and oxygen flow to the skin and capillaries, the cellular metabolism also increases and the capillary walls strengthen.
Red light therapy also notably boost lymphatic flow. Why is this important? Because it is estimated that without lymphatic flow, the average resting person would die within 24 hours. (John E. Hall PhD)
Near-Infrared (NIR) Light Therapy
Near-infrared is helpful when it comes to the regeneration of deeper structures such as tendons, bones, and cartilage; orthopedic and musculoskeletal problems. Near-infrared may also be useful for kidney problems. Anecdotal evidence suggests it could be a powerful therapy for kidney failure. (Dr. Mercola)
About 40% of the sunlight spectrum is near-infrared.
Anything which has a temperature puts out heat or infrared light.
Infrared light has a range of wavelengths, just like visible light has wavelengths that range from red light to violet.
Near-infrared light is closest in wavelength to visible light and is actually not hot at all.
NIR wavelengths (typically 850nm or 880nm) have been reported as penetrating deeper than other light wavelengths through skin and bone.
Researchers working with NASA have found that light therapy using NIR LEDs operate by activating color-sensitive chemicals in body tissues, stimulating the process in a cell’s mitochondria.
Three major photo acceptor molecules in mammalian tissues are known to absorb light in the NIR range: hemoglobin, myoglobin, and cytochrome c oxidase. Of the three, cytochrome c oxidase has been associated with energy production.
While the eye effectively perceives and distinguishes visible light, infrared (wavelengths longer than red) is perceived as heat when it is absorbed by the skin and converted into energy of the molecules of the skin. (Carnegie Mellon University)
Near-infrared is important as it primes the cells in your retina for repair and regeneration, which explains why LEDs — which is devoid of infrared — are so harmful to your eyes and health. (Dr. Mercola)
Yellow (Amber) Light Therapy
It’s thought to be the “botox” of light therapy.
It encompasses wavelengths from 570nm to 620nm, and it has a shallow skin penetration.
Yellow light has calming and soothing benefits that are ideal for treating a host of skin issues, including but not limited to: rosacea, inflammation, redness, irritation and wrinkles.
Yellow light therapy can also help reverse the damaging effects of UV radiation on the skin.
Yellow light works to heal the skin by eradicating waste, boosting lymphatic flow, and promoting the growth of new skin cells.
It is believed that the reason yellow light therapy effectively reduces the symptoms of redness among many rosacea sufferers is that the blood vessels can reduce in size following treatment. As a result, they and their red color become less visible. This action makes LED yellow light therapy sessions extremely safe and appropriate for all skin types, including those that are sensitive and reactive.
You can safely combine yellow and red light to maximize the benefits to your skin.
Blue Light Therapy
Blue light has been shown to generate singlet oxygen which attacks the bacteria that causes acne.
It’s also been used since the late 1950s to help treat jaundice in newborn babies. The most effective wavelengths range between 460-490nm. (Anadi Martel)
Studies show that blue light treatments are most appropriate for people with mild to severe acne since blue light is effective for killing off bacteria in the skin.
Blue light therapy works with a photosensitizing agent, which sets off a chain reaction to destroy damaged cells (i.e. those with cancer).
It’s used by used by oncologists, cosmetic surgeons, optometrists, and dermatologists.
It’s especially helpful at treating multiple types of cancer, especially those with tumors or growths that lie close to the skin’s surface. For blue light therapy to be successful, the light must be directly applied to the diseased tissue. Since the light can’t penetrate much further than the surface of the skin, it’s hard to target diseased cells beyond about 1 cm of the light source. (University Health News)
It can be administered in a dermatologist’s office or in your home.
There is minimal recovery time, although treatment might have adverse side effects: mitochondrial DNA damageand free radical production in epithelial cells.
Blue wavelengths are helpful for relieving pain; however, extended exposure can cause damage to the retina.
Green Light Therapy
Green light falls between 515nm and 520nm in the spectrum.
It can be used to target dark circles, pigmentation, broken capillaries and sunspots. It also calms irritated or over-stimulated skin.
One of the more common uses for green light skin therapy is to help improve skin pigmentation damage that has occurred as a direct result of overexposure to the sun’s UV rays, age spots and hyper-pigmentation.
Green light has a direct effect on melanocytes, which are the cells responsible for producing melanin (the pigmentation located in the lower layer of your skin).
How to Use Light Therapy
It’s important to realize that photobiomodulation is highly biphasic in dose, meaning the benefit can disappear by using too much light. One factor to take into consideration is the power density, measured in milliwatts per square centimeter. The second factor is the dose, which is typically calculated in joules per square centimeter. The third factor is the frequency of the light coming from the device you’re using. (Dr. Mercola)
As a general rule, an ideal power density is around 10 milliwatts per square centimeter. (Dr. Mercola)
Light therapy can be administered via continuous wave (CW) light or pulsed wave (PW) light.
Most of the photobiomodulation devices on the market today use a continuous wave, not pulsed, so there is no frequency.
When LED lights are pulsed, body tissues can heal more rapidly. Comparatively, a continuous, steady light beam can remove/dull pain, reduce inﬂammation and allows muscle tissue to relax.
“By and large, pulsing is better than continuous wave, and there is quite a bit of evidence [for this]…maybe not a huge amount better, but definitely better. The optimum frequency is somewhere between 10 and 40 hertz. There was a study from Massachusetts Institute of Technology that got a lot of publicity when they used 40-hertz light flashing into the eyes to treat Alzheimer’s in mice.” – Michael Hamblin (Dr. Mercola)
In general, the effects of using light therapy are cumulative and will get better over time, which means that you may eventually be able to use the light for less time in order to accomplish the same goals.
“Junk light” and how it can affect human health
Melatonin is suppressed by light in the blue wavelengths – between 470-480 nm. (Physiology.org)
Studies looking at light at night vs. cancer rate (even taking into account social and economic confounders) mostly show an increased risk of breast cancer due to light at night.
LEDs sabotage health and promote blindness. Limit your exposure to blue light during the daytime and at night. Swap out LEDs for incandescents or low-voltage incandescent halogen lights. (Dr. Mercola)
Biological effects of artificial lighting fall into 3 main categories:
Disturbance of the circadian rhythm
Risk of possible deterioration of the retina in the eyes
Impact of excess flickering
Overexposure to artificial blue light can disrupt your natural body clock, which can subsequently lead to a number of health concerns overtime, including but not limited to: heart disease, weight gain, insomnia, mood disorders, diabetes, and even cancer.
The photons from the blue and ultraviolet part of the spectrum have the most energy and therefore have an increased potential to damage the sensitive cells of the cornea, the lens, and the retina when fully exposed to them. (Anadi Martel)
“Mal-illumination” is when you get too much of the wrong kinds of light and too little of the right kinds, and at the wrong times of the day. The vast majority of people living in the modern world are suffering from chronic mal-illumination and don’t even realize it. This can have widespread effects on our brain and organ function, immune system, energy levels, mood, neurotransmitter balance, and hormone levels. (Ari Whitten)
A recent study from the University of Toledo found that overexposure to blue light (like that from LED screens found in our digital devices) can lead to macular degeneration in the eyes over time, and macular degeneration is the leading cause of blindness.
Kids’ eyes may be even more sensitive to junk light than adults’ because their eyes are still growing.
Many of your favorite and most frequented venues use artificial lighting to illuminate public space. These include offices, gyms, malls, airports, grocery stores, and more. While the LED revolution has helped businesses stay open longer, it’s also led to a daily overexposure to junk light for many people.