TL;DR: Skin is affected by exposure to UV irradiation from the sun and repeated exposure to harmful factors in the environment is noted to cause the typical photo aged skin having coarse wrinkles. However, the effect of sun-exposure causing these wrinkles is difficult to quantify or measure.
Skin, like many other organs, undergoes deleterious changes with the passage of time and associated hormonal and dietary variations. Unlike most other organs, however, skin is also directly affected by exposure to the environment, especially UV irradiation from the sun. Chronic exposure to UV irradiation causes an aged phenotype (photoaging) that is superimposed with aging caused by the passage of time (chronological aging). As a result, areas of the body that are frequently exposed to the sun such as the face, neck, forearms, or back of the hands acquire visible signs of aging more rapidly than other areas of the body. Source: Natural and Sun-Induced Aging of Human Skin
- Chronic sun exposure causes photoaging. Naturally aged and photoaged skin tend to share similar biochemical and cellular features but are clinically distinct.
Passage of time and repeated exposure to harmful aspects of the environment alter both the epidermal and dermal compartments of the skin. Clinically, chronologically aged skin appears thin, dry, and finely wrinkled. Photoaged skin typically appears leathery, lax, with coarse wrinkles, “broken”-appearing blood vessels (telangiectasia), and uneven pigmentation with brown spots (lentigines). Source: Natural and Sun-Induced Aging of Human Skin.
- Wrinkling and sagging of the skin is accelerated by repeated sunlight exposure.
These findings suggest that the Ue* and Uv* changes observed in human facial skin resemble the actinic aging caused by chronic UV exposure and that this animal model could serve as a useful and reliable tool to analyze the mechanism(s) involved in the UV-induced formation of wrinkling and sagging. The above findings strongly indicate that wrinkling and sagging of the skin is engendered by the preceding reduction of skin elasticity, which is accelerated by repeated sunlight exposure. Thus, the next mechanism to clarify is how skin elasticity is attenuated by repetitive UV irradiation. Source: Biological Mechanisms Underlying the Ultraviolet Radiation-Induced Formation of Skin Wrinkling and Sagging I: Reduced Skin Elasticity, Highly Associated with Enhanced Dermal Elastase Activity, Triggers Wrinkling and Sagging.
- Sunlight exposure is one of the several factors contributing to premature aging of the face along with the formation of coarse wrinkles.
With all the elements described in this study, we could calculate the importance of UV and sun exposure in the visible aging of a Caucasian woman’s face. This effect is about 80%. The interactions between chronological and photo-induced aging are complex, and the quantification of only the effect of sun-exposure is difficult to obtain. Our approach of using new descriptive skin-aging atlases is a solution to specify the extrinsic influence. Twenty-two clinical signs are used to describe and assess facial aging, wrinkles and skin texture, sagging of tissues, pigmentation manifestations, and vascular disorders. This study seems to confirm that pigmentation heterogeneity is a pure photoaging sign, whereas sagging of tissues is essentially a result of chronological aging. Vascular disorders could be considered as a precursor of future photoaging. Wrinkles and skin texture are influenced by both extrinsic and intrinsic aging, depending on the behavior of the individual with regard to the sun. The study confirms the accountability of sun exposure in premature aging of the face. Source: Effect of the sun on visible clinical signs of aging in Caucasian skin