This is a wonderful study that goes against conventional ideas regarding Visible Light (VL). There is still so much we are learning about light radiation and how it effects the body. Understanding that we know very little, we should be protecting ourselves as much as possible in any environment that could create potential harm. The full journal is linked below, but here is the condensed purpose and conclusion behind the study.
Visible light (400–700 nm) lies outside of the spectral range of what photobiologists define as deleterious radiation and as a result few studies have studied the effects of visible light range of wavelengths on skin. This oversight is important considering that during outdoors activities skin is exposed to the full solar spectrum, including visible light, and to multiple exposures at different times and doses. Although the contribution of the UV component of sunlight to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology in terms of inflammation, and limited information is available regarding the role of visible light on pigmentation.
The purpose of this study was to determine the effect of visible light on the pro-pigmentation pathways and melanin formation in skin. Exposure to visible light in ex-vivo and clinical studies demonstrated an induction of pigmentation in skin by visible light. Results showed that a single exposure to visible light induced very little pigmentation whereas multiple exposures with visible light resulted in darker and sustained pigmentation. These findings have potential implications on the management of photo-aggravated pigmentary disorders, the proper use of sunscreens, and the treatment of depigmented lesions.
Taken together these results demonstrate that in addition to UV, VL can have significant impact on producing uneven pigmentation in skin which is a main factor in photoaging. Furthermore this is the first report that preconditioning of the skin with VL, followed by multiple exposures to VL, can result in pigment formation. Thus photoexposure and photodamage should not be considered strictly as a result of UV exposure since the skin is exposed to whole spectra of wavelengths including VL, and VL can induce photodamage pathways in a manner similar to UV.