Blue light, particularly emitted by the sun, LED bulbs, computers, and mobile phones, has effects on the skin and is suspected of causing a dull complexion. Is this hypothesis supported by scientific studies? Let's explore this question together.
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- Blue light and dull complexion: myth or reality?
Blue light and dull complexion: myth or reality?
Dull complexion: A consequence of exposure to blue light?
Also known as high-energy visible light, blue light, which emits at wavelengths between 400 and 500 nm, is part of the visible light spectrum. Its energy is lower than that of ultraviolet radiation, well known for its effects on the skin, which means it can penetrate deeper into the dermis. Exposure to blue light, whose main emission source is the sun, is not without consequences for the skin. While it can be used for therapeutic purposes, for example to treat acne, psoriasis, or certain precancerous lesions, blue light could also have negative effects on the complexion.
Indeed, several studies have shown that exposure to this light stimulates the production of free radicals, particularly reactive oxygen species (ROS) and reactive nitrogen species (RNS). One study notably revealed that irradiating cultured human keratinocytes with a dose of 41.35 J/cm² of blue light at 453 nm induced a significant production of ROS and RNS in less than an hour. In vivo, irradiating human skin with blue-violet light (100 J/cm², 380 to 495 nm) also resulted in a notable decrease in carotenoids, antioxidants naturally present in the skin that serve to neutralize free radicals and protect the skin. It is important to remember that these unstable molecules can attack cellular structures, such as DNA, membrane lipids, and structural proteins like collagen.
In addition to accelerating photoaging, this oxidative stress can damage the membranes of keratinocytes, which make up about 80% of the cells in the epidermis, and disrupt their renewal. This slows down their proliferation and leads to an accumulation of dead cells on the skin's surface. The result is a thick and irregular stratum corneum, incapable of properly reflecting light on the skin, giving it a dull and tired appearance.
Furthermore, blue light also influences the genes of the circadian clock, also known as CLOCK genes, which regulate the biological rhythms of many cellular processes, including those in the skin. These genes, such as BMAL1 and PER1, play a significant role in maintaining the cycle of keratinocytes. However, studies have shown that exposure to blue light can reduce the expression of PER1 in human keratinocytes, thereby disrupting the skin's biological clock. In addition, blue light alters the activation of ECTO-NOX proteins, which are involved in the synchronization of the biological clock, influenced by both light and melatonin.
These disruptions can have a direct impact on the complexion by slowing down the skin's nocturnal repair and regeneration processes. Indeed, the proliferation of keratinocytes and cellular renewal usually peak during the night. This is why a lack of sleep can lead to a dull skin complexion. However, studies have shown that keratinocytes from ten women who work at night and have irregular circadian cycles exhibited a significantly reduced clonogenic capacity compared to keratinocytes from ten women who work during the day. Clonogenic capacity refers to a cell's ability to divide and form a colony of identical cells from a single mother cell. It reflects cellular proliferation, that is, the ability of cells to multiply effectively, one of the pillars of keratinocyte renewal. This decrease in clonogenic capacity promotes the accumulation of dead cells on the skin's surface, thus dulling the complexion.
These various elements suggest that blue light can indeed alter the complexion. Fortunately, there are solutions to protect oneself from it.
Sources
DARVIN M. & al. Blue-violet light irradiation dose dependently decreases carotenoids in human skin, which indicates the generation of free radicals. Oxidative medicine and cellular longevity (2015).
PARIS M. & al. Human long-term deregulated circadian rhythm alters regenerative properties of skin and hair precursor cells. European journal of dermatology (2018).
KOLBE L. & al. High-energy visible light at ambient doses and intensities induces oxidative stress of skin-Protective effects of the antioxidant and Nrf2 inducer Licochalcone A in vitro and in vivo. Photodermatology, photoimmunology, photomedicine (2020).
LIU W. & al. Direct and Indirect Effects of Blue Light Exposure on Skin: A Review of Published Literature. Skin pharmacology and physiology (2022).
GOLDUST M. & al. The impact of blue light and digital screens on the skin. Journal of Cosmetic Dermatology (2023).
ROBIC G. & al. Yellowness in skin complexion: Analysis of self-perception of women in China evaluated against clinical parameters of yellowness. Skin Research and Technology (2024).
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