LED Light Therapy and Hyperpigmentation
There is a vast array of mythology surrounding LED light therapy – most of it created by clever marketing directors of light therapy manufactures. This leads to a lot of confusion in the skin care community and the same questions being asked over and over. Two related questions routinely asked are, “Does the heat from LED devices cause hyperpigmentation” and “Does green light effectively treat hyperpigmentation?” The short answer to both of those questions is no, but let’s elaborate further.
Let’s start by discussing the pathology of hyperpigmentation. “Melanin, a natural skin pigment, plays an essential role in preventing ultraviolet light-induced skin damage.
Stimulation of the melanocytes results in the release of tyrosinase, an enzyme that converts tyrosine through chemical reactions to produce melanin. The melanin is then transported by the dendrites to the keratinocytes. Deposition of melanin is determined by whether these dendrites are epidermal or dermal. Hyperpigmentation results from an accelerated increase in the production of melanin by the melanocytes.”1
There are multiple factors that increase the incidence of pigmentation, including ultraviolet radiation, hormonal alterations, genetic predispositions, ethnicity, and inflammatory processes. Nowhere in the clinical literature is heat found as a cause of hyperpigmentation, at least not the kind of heat generated by modern LED devices. Light emitting diodes do not produce heat, which is why they last so long. As a result, the surface temperature of the skin should be raised no more than a few degrees Celsius during light therapy treatment. In fact, the FDA has a performance standard for LED light therapy devices that requires the demonstration of raising the surface of the skin temperature to 40 degrees Celsius, which is not much higher than normal body temperature.
The false association between the increased incidence of hyperpigmentation during the summer months and increased ultraviolet sun exposure may be the cause of confusion. While it is indeed warmer in the summer, it is not the heat that increases hyperpigmentation, rather it is the increased exposure to ultraviolet light energy. Fortunately, the wavelengths of light energy incorporated into LED light therapy devices are well above the ultraviolet range, so there is no risk of triggering hyperpigmentation from using such a device.
It should also be noted that the early generations of LED light therapy devices used an electronic design borrowed from photodynamic therapy, where high doses of light energy were used to trigger photo-activated topically applied products. These devices do produce a significant amount of heat, requiring cooling fans to keep them from over-heating the device or the patient. Accordingly, look for LED devices that do not require such cooling mechanisms. If you want to know more about the cause of hyperpigmentation beyond ultraviolet light exposure, Dr. Erin Madigan-Fleck has recently written a brilliant paper on the subject.
From a search of the clinical literature, LED light therapy is shown to be effective in treating hyperpigmentation. Again, let’s start with the mechanism of action in treating hyperpigmentation with LED light therapy. LED light energy, “significantly reduced melanin production and tyrosinase expression, not only in a normal human melanocyte monoculture both with and without forskolin stimulation but also in a three-dimensional multiple cell type culture. It reduced melanin content through inactivation of the apoptosis signal-regulating kinase and extracellular signal-regulated kinase half pathways. The level of phosphorylated cyclic AMP response element-binding protein was also decreased by LED irradiation. Moreover, LED irradiation reduced melanogenesis through decreased expression of tyrosinase family genes (tyrosinase-related protein-1 and 2, and microphthalmia-associated transcription factor). These results indicate that LEDs could potentially be used to treat melanin-overproducing skin conditions.”2
In LED light therapy, depth of penetration is determined by wavelength. The longer the wavelength of light energy, the deeper it reaches into the tissue, within a well-defined range. In recent clinical studies on hyperpigmentation, near-infrared light energy was demonstrated to reduce the appearance of hyperpigmentation without tissue damage, as it easily reaches the dermis, down-regulating hyperactive dermal melanocytes without side effects. Green wavelengths are simply too short to reach the melanocytes in the dermal layer.
These findings do not negate the fact that some skin care professionals can achieve favorable anecdotal results using green light to treat hyperpigmentation. However, this modality of treatment is not supported by robust, peer-reviewed, and published clinical data. Red and near-infrared wavelengths of light energy are much longer than green light and therefore, more effective in reaching the target tissue in the treatment of hyperpigmentation.
Kim, Jeong Mo, Nan-Hyung Kim, Yu Shun Tian, and Ai-Young Lee Dongguk. “Light-Emitting Diodes at 830 and 850 Nm Inhibit Melanin Synthesis In Vitro.” Light-emitting Diodes at 830 and 850 nm Inhibit Melanin Synthesis In vitro | HTML | Acta Dermato-Venereologica, 2011. https://www.medicaljournals.se/acta/content/html/10.2340/00015555-1319.
Barolet , Daniel. “Dual Effect of Photobiomodulation on Melasma: Downregulation of Hyperpigmentation and Enhanced Solar Resistance-A Pilot Study: JCAD: The Journal of Clinical and Aesthetic Dermatology.” JCAD, January 30, 2019. https://jcadonline.com/effect-photobiomodulation-melasma/.
Pam Cushing is a registered nurse with over 35 years of experience in emergency medicine. She has worked in the field of aesthetics for over 15 years, full-time for the last five years. Cushing holds a degree at the master’s level, with commendation, as well as a post-graduate diploma in aesthetic medicine, with merit. She is an independent nurse prescriber in the United Kingdom. Cushing is a consultant educator for a couple of companies educating in injectables, skin resurfacing and chemical peel, microneedling, and LED. She thrives on being able to educate, motivate, and encourage others to grow and develop professionally. She is passionate about skin and the benefits of aesthetics in improving the confidence and quality of lives. Cushing believes our key role is to educate the consumer on appropriate treatment modalities with the focus on maintaining skin health.
Published in The LED Playbook