Light Therapy for Skin Health
Social media is ablaze these days with stories and images of people using light therapy to improve their skin health. Women of all ages can be seen irradiating their faces with devices ranging from illuminated panels to Halloween-like face masks, which they claim reduces the appearance of lines and wrinkles, improves skin elasticity, and treats breakouts. Is this just more social media hype, or can light therapy really be used to improve skin health? And what exactly is light therapy anyways?
What is Light Therapy?
Light therapy (also known as photobiomodulation) is the application of light with specific wavelengths to the body for the purposes of influencing biology. The most common form of light therapy uses red light (RL), which is visible as the color red, and/or near infrared light (NIRL), which is not visible but can be felt as heat. The RL used in light therapy usually ranges from 600 to 700 nanometres (nm), with the unit nm referring to distance the light wave travels in one cycle. The NIRL used in light therapy usually ranges from 800 to 900nm. Blue light (BL), which ranges from around 450 to 495nm, is also used in many light therapy products.
RL, BL, and NIRL are naturally produced by the sun, which gives off solar radiation. The term radiation describes energy that is transmitted in the form of waves or particles. The spectrum of light in our environment consists of both light we can see (visible light) and light that our eyes can’t perceive (invisible light). This is called the electromagnetic spectrum. The visible light spectrum is quite narrow, consisting of wavelengths that range from 400 to 700nm and span from violet to red in color. BL and RL are part of this visible light spectrum, while NIRL is not.
Although the amount of solar radiation is not constant, approximately 40% percent of the light from the sun is visible light, which can be divided by color and wavelength. RL and BL are part of visible light. NIRL waves lie just beyond the “red” end of the visible light spectrum, so we don’t see them. NIRL is part of the “infrared” spectrum, which consists of both NIRL and far infrared light (FIRL). Infrared light makes up 50% of the solar radiation that reaches the earth. The remaining 10% of the light from the sun is also invisible, falling just beyond the opposite “violet” end of the visible spectrum to IR. This is called ultraviolet light (UVL).
Red and near infrared light therapy is the application of artificially generated light in the red and near infrared spectral bands. The term “red light therapy” usually describes the use of both RL and NIRL, although only the red light produced by the device is visible to the naked eye. IRL can still be perceived by the body as heat when it contacts skin. Red and NIRL therapy does not involve the use of UV rays, although UV can (and is) sometimes used in some forms of light therapy. Other forms of light therapy include light in the blue, green and/or yellow spectrums. RL/NIRL is the most used form of light therapy, although BL is also often used in light therapy for skin conditions. Different colors of light have different depths of skin penetration, with RL and NIRL penetrating the deepest.
Wait a Minute – Isn’t the Sun Bad For My Skin?
According to most national health agencies, sun exposure should be limited because it increases the risk of skin cancer. The FDA recommends avoiding the sun between 10am and 2pm and using sunscreen and sun blocking clothing and sunglasses the rest of the time, even on cloudy days. The CDC gives guidelines to schools to provide shade for students and employees that work outside, and to encourage them to use sunscreen while at work and school. And the American Academy of Dermatology Association recommends that everyone use sunscreen or sunblock, every day.
However, excessive sun avoidance may also be harmful to human health. It has recently been estimated that around 340,000 excess deaths per year in the US are due to insufficient sun exposure. This is, at least in part, because sun is needed for vitamin D production, which is essential to health. Vitamin D is made in the skin when exposed to UV light. Many people are modern society are vitamin D deficient, which can have serious consequences, including the development of age-related diseases, diabetes, cardiovascular disease, multiple sclerosis, and infectious diseases. This suggests that sun exposure plays an important role in health, which is consistent with the evolution of life on earth alongside solar radiation for billions of years.
UV rays are the component of solar radiation that are the main culprits in causing skin cancer. But as already mentioned, the sun contains many other different types of light rays. Like UV rays, these other types of rays are important regulators of physiological processes including circadian rhythms and hormone production, but they do not show a similar association with cancer. This suggests that we should aim to increase our exposure to healthy solar radiation while limiting UV exposure, although some UV exposure is essential. One way to do this is by using light therapy devices that do not emit UV light.
It should be noted that there is some controversy over whether BL can have harmful effects on the skin. While BL from electronic devices may not be healthy, BL from light therapy devices has been shown to be beneficial in the treatment of some skin conditions, such as acne, as will be described later.
There is also some controversy over whether NIRL can have harmful effects on the skin, with some sunscreens advertising that they protect against “harmful” UVL and IRL. However, evidence of harm from NIRL came from studies using light at very high intensity that were not representative of the IRL dose obtained from the sun. As such, experts in the field have concluded that when it comes to the skin, IRL does “more good than bad”. Harm can be avoided by using IRL devices that mimic the intensity of the sun, but do not exceed it.
How does Light Therapy Improve Skin Health?
There are a wide range of biological effects of light therapy which are induced by the application of light to the body. Effects occur both when light is applied to the skin as well as when it enters through the eyes.
Light is absorbed in cells by molecules called chromophores, many of which are found inside the mitochondria. Mitochondria are the powerhouses of the cell, which make the energy currency of the cell known as ATP. Mitochondria are also involved in regulating the production of molecules called reactive oxygen species (ROS), which play a role in normal cellular function but can be harmful in high amounts. This is known as oxidative stress.
Through its effects on mitochondria, light therapy can increase cellular energy production and modulate oxidative stress. In the skin, this increased energy can be used to support normal processes such as collagen and elastin production. And by modulating ROS production and oxidative stress, there is a shift towards skin rejuvenation rather than skin breakdown.
The effects of light on cells extend beyond ATP and ROS, although these are the most well-known. Other effects include modulation of nitric oxide (NO), increased angiogenesis (blood vessel formation), and increased antioxidant enzyme activity. A deep dive into the science shows a vast network of cellular pathways that are influenced by light, many of which support the development and maintenance of healthy skin. Light truly has powerful effects on human biology.
What Skin Conditions are Helped by Light Therapy?
Acne – Acne, also known as acne vulgaris, is a common skin condition, affecting nearly 10% of people worldwide. Prevalence is highest in adolescents, with up to 85% having acne at some time during this period. Acne is not only painful, but it can also have adverse effects on many aspects of life, including social, psychological, and economic. Since acne has been observed to respond positively to sun exposure, a variety of phototherapy treatment approaches have been used. Light therapies treat acne through anti-inflammatory and antimicrobial effects, and by disruption of sebaceous gland function. RL, IRL, and BL have all been found to effectively treat acne. Inflammatory acne is more responsive to light therapy than non-inflammatory acne, and studies have even found it to be superior to some medications.
Anti-Aging – The anti-aging effects of phototherapy are often referred to as “skin rejuvenation”. This is an umbrella term that includes outcomes like increased collagen synthesis, increased elastin production, extracellular matrix regeneration, regulation of oil production, and regulation of the pigment producing cells of the skin. Clinically, these manifest as reduced wrinkles, improved skin appearance, and improved skin pigmentation. Studies show results such as smoother skin; wrinkle reduction and improved skin elasticity; and normalization of skin pigmentation. The effect of red light therapy on wrinkles can be quite dramatic, with one study showing a 30% decrease in eye wrinkle volume. Most skin rejuvenation studies use RL and NIRL. Importantly, the use of light therapy to regenerate skin is “non-ablative”, which means that it doesn’t harm the epidermis of the skin. This contrasts with many popular anti-aging treatments such as microneedling, chemical peels, and microdermabrasion.
Psoriasis – Psoriasis is an inflammatory autoimmune skin disease that causes scaly dry patches made up of a buildup of skin cells. Psoriasis is most commonly found on joints (like elbows and knees) but it is possible to find them on any part of the body. Psoriatic patches are referred to as “plaques”. Psoriasis is a common condition, affecting up to 3% of the population or approximately 7.5 million US adults. Both red and NIRL therapy are recommended in the treatment of psoriatic plaques, even in patients resistant to conventional treatment. Red and NIRL therapy improves psoriasis through many different mechanisms, including improving mitochondrial function and decreasing inflammation.
Hair Loss – Hair follicles are found embedded in the dermis of the skin. The ability of light therapy to induce hair growth was observed in studies conducted more than 50 years ago. Early clinical trials used primarily RL, and the effectiveness of these studies led to the development of several RL therapy devices for hair loss. Subsequent studies have shown that NIRL light also stimulates hair growth, with RL and NIRL improving hair growth in androgenetic alopecia, which is the most common type of hair loss that affects both men and women. Light impacts hair growth through effects on mitochondria, which lead to increases in the length of time the hair follicle spends in the growth phase.
Eczema - Eczema (also called atopic dermatitis) is defined by the World Allergy Organization as “an inflammatory, chronically relapsing, non-contagious and extremely pruritic skin disease.” The prevalence of eczema is estimated to be 2-5% in the general population, and it is even more common in children and younger adults. Eczema is characterized by skin inflammation, so anti-inflammatory treatments are often helpful. In a study of patients with eczema associated with orthopedic implants, 50% of those who were treated with NIRL showed a decrease in skin itching and lesions. This may be due to modulation of the immune system.
Melasma/Hyperpigmentation – Hyperpigmentation of the skin is caused by an overproduction of the pigment melanin. Hyperpigmentation is most often seen in melasma, a condition characterized by dark colored patches, usually on the face. Because melasma and hyperpigmentation are triggered by exposure to UV light, which increases melanin production, patients are advised to limit sun exposure. However, exposure to RL and NIRL does not have the same effect, and in fact, may decrease hyperpigmentation. Most studies have combined topical medicines with light therapy from lasers, but LED lights have also been shown to decrease hyperpigmentation.
Wound Healing – Wound healing is a complicated process that includes inflammation, growth of new blood vessels, and skin repair. Application of both red (RL and NIRL) and BL have been found to help with wound healing, with some studies showing that BL may be more effective than RL, although both are beneficial. BL is especially effective at killing bacteria that colonize wounds, impair healing, and cause infection, while RL stimulates fibroblasts, blood vessel formation, and collagen synthesis. This suggests that RL and BL could be used together for a synergistic effect on wound healing.
Scars – There are many ways that light therapy can decrease scars. As already mentioned, RL and BL can decrease the severity of acne, which reduces the likelihood of scarring. RL and BL also speed up wound healing, which similarly minimizes scar formation. In addition, light therapy (specifically NIRL) can decrease the formation of keloid and hypertrophic scars. These types of scars are due to an excessive growth of scar tissue. RL has similarly been found to reduce post-operative scarring.
Cold sores – Cold sores are caused by the herpes simplex virus type 1 (HSV-1). The World Health Organization estimates that up to 67% of people worldwide are infected with HSV-1, although many people don’t have symptoms. Symptomatic HSV-1 causes painful blisters on the lips that last 10-14 days, and there is no curative treatment. Although there haven’t been many studies in this area, research to date has been promising. RL has been shown to decrease both the frequency of symptomatic HSV-1 episodes and also to prolong the asymptomatic interval. These effects are probably mediated by the action of light therapy on the immune system.
Radiodermatitis – Radiodermatitis is a common side effect of radiation therapy, affecting as many as 95% of treated patients. In radiodermatitis, skin cells are damaged by radiation, causing itching, dryness, redness, swelling, loss of body hair, pain, skin atrophy, and fibrosis. Both RL and NIRL have been found to be beneficial when used as an adjunct treatment along with radiation therapy to decrease its adverse effects on skin. Specifically, light therapy decreases the severity of radiodermatitis and increases patient’s quality of life. Importantly, light therapy had no harmful effects on tumor growth or overall survival in these studies. A recent systematic review concluded that light therapy “in the red or near-infrared spectrum (630–905 nm) is safe and efficient in the management of various complications of oncological therapy and can be applied throughout radiotherapy and/or up to 30 days after.”
Choosing a Light Therapy Device
With so many light therapy devices currently on the market, how can you know which device is best for you? Here are five issues to consider.
Light source - Light therapy is administered using either laser or LED lights. While early light therapy research was done using lasers, LED lights have become much more popular over the last decade. The research described in this article includes both types of light sources. In 2018, Dr. Michael Hamblin – the world’s leading light therapy expert – concluded that LED lights using comparable parameters to lasers performed “equally well”, which is very important because LED powered light therapy devices can be made at a fraction of the cost of laser devices. Laser powered devices are still a favorite in medical offices, which makes sense given their high cost and higher risk of adverse effects such as skin irritation. LED powered devices are more often sold for at home use, although some medical clinics also use them. Consumers can rest assured that using LED powered devices for the treatment of skin disorders is well supported by research evidence. For at home use, look for a device that uses LED lights as safe and affordable option.
Light Color/Wavelength – As described in this article, different light wavelengths including red, blue, and near infrared have been used in studies of light therapy to treat skin disorders. While some studies show benefits specifically to using one light wavelength, others have observed benefits from more than one form of light. Some conditions, such as acne and skin wounds, are especially well suited to combination light therapy. As a result, multi-wavelength devices will be the most versatile. Ideally, users should be able to control each type of light independently, and to combine them if desired.
Light Intensity – Light intensity refers to the amount of light being delivered by a device. It is also referred to as irradiance. This describes the amount of light energy your skin receives over a period of time and is usually measured in mW/cm2. The amount of light your skin receives, which is a function of time and intensity, is referred to as the “dose”. In terms of intensity, it has been found that it is ideal to mimic the intensity of the sun, which is around 24 mW/cm2 at the skin. This is described as the “sweet spot” between higher intensities, which can have harmful effects, and lower intensities, which will have no effect at all. Many devices on the market are at a much higher intensity than the sun. Exposing the skin to too high an intensity, especially for a prolonged period of time, will likely do more harm than good. When it comes to light therapy, more is not better, so choose a sun-mimicking product and don’t overdo it when it comes to treatment frequency and duration.
Device Type – Light therapy devices come in many shapes and sizes. To choose the right one for you, first identify what area(s) of the body you want to treat. If there are multiple body parts to be treated, you should choose a versatile device like an LED panel that can easily be applied to different target areas. LED panels can be used to treat most body parts, including the face, chest and back. Or, if you want to target a particular body part (such as the face), you can choose a product that is designed specifically for that area (for example, a mask). Second, you should consider how and where you intend to use the product. If you would prefer to lie down while doing a treatment, you would do better with a portable LED device rather than an LED panel. Portable devices are also the best choice if you would like to have the option of moving around during your treatment. Every person’s needs are unique, but there are many different device options to choose from.
Education – While light therapy education will not change the specific functionality of a device, it does have the potential to profoundly impact how someone uses the technology. When a company provides evidence-based education that teaches consumers why, how, and when to use a product, devices can be used to better support healing. Look for products with accompanying education and instructions for use, whether in printed and/or digital formats. You can also look for companies that provide support by phone or email to current or prospective customers.
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Conclusion
As you can see, using light therapy to improve skin health is much more than just social media hype. Research has demonstrated that it is a safe and effective treatment for a wide range of skin conditions that afflict a large percentage of the population. With the increased availability of LED devices, people can now affordably use light therapy in the comfort of their own home. Choosing the right product is easy: Look for one that mimics the intensity of the sun, provides the right light wavelengths for the condition(s) you’re treating, and fits into your lifestyle.
