Actinic Damage: The Major Cause of Skin Aging

The authors have previously reported on the deleterious effects of sunlight on human skin tissue. Despite ongoing evidence that actinic damage and skin ageing are caused not only by ultraviolet radiation, but also visible light and near-infrared energy, few studies have focused on the additive impact of the sun’s total energy. In the past, ultraviolet radiation was assumed to be the only biologically significant factor in skin actinic damage, but in recent decades this view has been considerably revised to include the impact of the sun’s complete energy reaching the earth affecting terrestrial life, including humans. In this paper, we summarize the evidence supporting actinic damage and the cumulative negative effects of ultraviolet, visible light and near-infrared radiation as the major cause of photoaging, pigmentation, vascular irregularity, muscle thinning, skin ptosis, photoimmunosuppression and photocarcinogenesis. Visible skin aging associated with actinic damage is differentiated from chronologic aging, which is less defined by the stigmata of photoaging associated with changes to skin tone, texture and laxity. Awareness of the biological effects of total solar energy output and understanding actinic damage may assist physicians and patients to seek comprehensive solar protection and repair strategies including sun avoidance and topical preparations that protect from ultraviolet, visible light and near-infrared as well as skin repair mechanisms including retinoids and DNA repair enzymes.