Much of what is believed about the subject of LED light therapy is urban mythology, based on sales spins and not in rigorous scientific evidence. Several of these myths relate to the relationship between LED devices, hyperpigmentation, and are perpetuated despite the fact that they are not supported by clinical research. Specifically, this article explores the myth that LED devices can cause hyperpigmentation.
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Most skin care professionals know from the general clinical literature that the primary cause of hyperpigmentation is exposure to ultraviolet light energy (350 nanometers to 400 nanometers) from the sun. This is not to be confused with exposure to heat. There is a false association between the warmer summer months and the increased incidence of hyperpigmentation. The truth of the matter is that the warmer summer months bring increased exposure to damaging ultraviolet light energy from the sun. This is completely unrelated to heat. In fact, light emitting diodes do not produce heat. LEDs are not bulbs, and they do not generate thermal energy, which is why they last so long.
Pregnancy, hormonal fluctuations, medications, and hyperthyroidism can also trigger hyperpigmentation of the skin. However, moving into the visible light spectrum, visible light (400 nanometers to 750 nanometers) energy can, on very rare occasions can trigger hyperpigmentation. The fundamental mechanism of action seems to be that light energy directly targets melanocytes in the skin to stimulate melanogenesis pathways. On these rare occasions, the darker the skin, the more severe and long-lasting the hyperpigmentation, particularly with Fitzpatrick type III and IV skin.
That said, clinical studies have indicated that the longer the wavelength of light energy, the less severe and shorter lasting the hyperpigmentation. The possible triggering of hyperpigmentation decreases rapidly in wavelengths longer than 465 nanometers. However, the fluence (or optical power) of light energy used in those studies is up to 10 times that produced by the market-leading LED devices. In fact, at the fluence levels of LED devices FDA-cleared for treating the skin, these studies show little or no triggering of hyperpigmentation, even in Fitzpatrick types III and IV skin.
More recently, there has been a rash of articles about blue light and the detrimental effects of over-exposure to the skin. The common thread in these articles seems to be the increased exposure received from consumer electronics, such as laptop computers, tablets, and smartphones.
However, the driving motivation in most of these articles seems to be the promotion, and in some cases, the outright commercialization of topically applied products that protect against blue light. Unfortunately, LED light therapy is left impugned by these articles, as there is no real distinction discussed regarding the differences between the blue light used in LED light therapy devices as compared to consumer electronics and direct sunlight.
In several of these articles on the risks of blue light exposure, researchers are evaluating fluency levels, which are orders of magnitude greater than that received in a 30-minute LED light therapy treatment. In fact, blue light exposure in the range produced by LED light therapy devices is shown to not trigger hyperpigmentation or other skin-damaging conditions.
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When it comes to LED and hyperpigmentation, skin care professionals should do as much scientific research as possible, along with reaching out to FDA-approved companies to confirm the best option for LED devices. While hyperpigmentation can occur, with the right device, these chances are increasingly little to none.
