Sun damage, or photoaging, occurs when exposure to ultraviolet (UV) radiation causes damage in your skin. UV radiation generates reactive oxygen species (ROS), which cause oxidative stress that can damage skin cells, collagen, and elastin. Over time, this damage can lead to uneven skin tone, fine lines, rough texture, and loss of elasticity.
Sun damaged skin is the result of cumulative UV exposure, even without visible sunburn. While sunburn may show more immediate signs like redness, dryness and discolouration, damage to deeper layers of the skin can take years before becoming more visible. At times, sun damage becomes more noticeable at the end of summer or after prolonged outdoor exposure.
How Does UV Light Cause Sun Damage?
There are 2 kinds of UV light that can pass through Earth’s atmosphere, both of which can damage the skin:
UVA light.
This form of solar radiation has longer wavelengths that penetrate deep into the dermis. By triggering damaging ROS in the skin, UVA light can contribute to the degradation of collagen and elastin fibres, and damages skin cells, contributing to loss of elasticity, uneven skin tone, and fine lines and wrinkles.
UVB light.
This type of solar radiation has shorter wavelengths and primarily affects the outermost layer of the skin (epidermis). UVB light is more likely to cause sunburn, but also triggers ROS that lead to visible signs of sun damage.