INTRODUCTION
The damaging effects of ultraviolet (UV) radiation on the skin are well studied and widely appreciated. For decades, dermatologists have stressed to our patients the importance of UV protection to ward off skin cancer and photoaging. UV radiation, however, comprises only 3-7% of total solar radiation reaching Earth’s surface.1 Visible light accounts for a much greater proportion of solar radiation and has more recently begun to gain attention, in large part due to growing concern over exposure to blue light (a form of visible light) emitted from artificial sources. Our ever-increasing reliance on laptops, smartphones, and tablets has stirred public interest in the consequences of visible light emitted from electronic devices. With the COVID-19 pandemic shifting many of us to remote-style work and study, this topic has become more relevant now than ever. What impact does exposure to blue light have on our skin? This article will review what we know about blue light, its impact on skin health, and what actions we can take with this knowledge.
What is Blue Light?
Visible light (400–700 nm) is the portion of the electromagnetic spectrum that is visible to the human eye and is responsible for general illumination.1 It comprises roughly 44% of solar radiation reaching sea level, but is also emitted by anything that produces illumination: light bulbs, televisions, smartphones, and so on.1,2 Compared to UV light, visible light penetrates deeper into the skin to a depth range of 90 to 750 μm.1 The color of visible light varies according to wavelength. Blue light is the portion of the visible light spectrum with the shortest wavelength (400–495 nm) and greatest energy.2,3 Blue light has anti-proliferative properties and has been utilized for therapeutic purposes in skin conditions including psoriasis and pre-cancerous lesions.2 Recent studies, however, have discovered potential harmful effects of blue light as well. There is growing evidence that blue light can induce erythema, pigmentation, and oxidative stress in the skin and potentially worsen photo-aggravated dermatoses.2,3
How Does Blue Light Impact Our Skin?
Pigmentation
Numerous studies have investigated the effect of visible light on skin pigmentation. The evidence is clear — visible light is capable of inducing pigmentation in melanocompetent skin.4-6 In a clinical study by Mahmoud et al, visible light resulted in both erythema and dose-dependent pigmentation in Fitzpatrick skin types IV-VI.4 Compared with pigmentation induced by UVA1 radiation in the same study subjects, visible light-induced pigmentation was both darker and more sustained. While UVA1-induced pigmentation faded rapidly, visible light-induced pigmentation remained unchanged at the end of the 2-week study period.4 No pigmentation or erythema was observed in Fitzpatrick skin type II, even at the highest tested dose.4 The pro-pigmenting doses of visible light used in this study are easily obtained from daily sun exposure, suggesting that solar visible light may have clinical implications in our darker-skinned patients.4
What is Blue Light?
Visible light (400–700 nm) is the portion of the electromagnetic spectrum that is visible to the human eye and is responsible for general illumination.1 It comprises roughly 44% of solar radiation reaching sea level, but is also emitted by anything that produces illumination: light bulbs, televisions, smartphones, and so on.1,2 Compared to UV light, visible light penetrates deeper into the skin to a depth range of 90 to 750 μm.1 The color of visible light varies according to wavelength. Blue light is the portion of the visible light spectrum with the shortest wavelength (400–495 nm) and greatest energy.2,3 Blue light has anti-proliferative properties and has been utilized for therapeutic purposes in skin conditions including psoriasis and pre-cancerous lesions.2 Recent studies, however, have discovered potential harmful effects of blue light as well. There is growing evidence that blue light can induce erythema, pigmentation, and oxidative stress in the skin and potentially worsen photo-aggravated dermatoses.2,3
How Does Blue Light Impact Our Skin?
Pigmentation
Numerous studies have investigated the effect of visible light on skin pigmentation. The evidence is clear — visible light is capable of inducing pigmentation in melanocompetent skin.4-6 In a clinical study by Mahmoud et al, visible light resulted in both erythema and dose-dependent pigmentation in Fitzpatrick skin types IV-VI.4 Compared with pigmentation induced by UVA1 radiation in the same study subjects, visible light-induced pigmentation was both darker and more sustained. While UVA1-induced pigmentation faded rapidly, visible light-induced pigmentation remained unchanged at the end of the 2-week study period.4 No pigmentation or erythema was observed in Fitzpatrick skin type II, even at the highest tested dose.4 The pro-pigmenting doses of visible light used in this study are easily obtained from daily sun exposure, suggesting that solar visible light may have clinical implications in our darker-skinned patients.4
