The Effects of UV Exposure on Ageing

What causes our skin to age?
Skin ages and loses its youthful appearance over time. Wrinkles develop on the forehead, fine lines appear around the eyes and mouth, and age spots surface on the hands.
There are several factors that affect how our skin ages. Intrinsic ageing is the natural ageing process that is determined by our genes; over time, our skin naturally becomes thinner, drier, and wrinkled. Extrinsic ageing is the premature ageing of the skin caused by environmental factors and lifestyle choices.
Though we cannot control the intrinsic ageing process, we can take action to help slow the effects of extrinsic ageing. One key preventative measure is to avoid sun exposure; up to 90% of ageing on exposed skin is due to the harmful effects of the sun.

What is photoageing?
Photoageing is premature ageing of the skin caused by repeated exposure to ultraviolet (UV) radiation, both from the sun and from artificial UV sources. “Photo” comes from the Greek word “phos” which means “light”. Therefore, “photoageing” refers to ageing of the skin caused by light.

How does sun exposure affect our skin?
Skin is composed of three layers: the outermost layer (the epidermis), the middle layer (the dermis), and the basement layer (the subcutis). The dermis contains collagen, elastin, and other fibers that give skin its smooth and youthful appearance. These skin-supporting fibers are damaged by UV radiation emitted from the sun.
UV radiation that affects the skin is composed of two different types of waves, ultraviolet A (UVA) and ultraviolet B (UVB). Shorter wave UVB rays mainly affect the epidermis and can cause sunburns, skin damage, and skin cancer. Longer wave UVA rays penetrate the epidermis and reach deep into the dermis where they damage the collagen and elastin fibers. The breakdown of elastin fibers causes the skin to sag, stretch, and lose its ability to rebound from damage. As such, UVA rays are responsible for much of the photoageing damage that is visible on the skin.

What are the signs of photoageing?
The signs of photoageing on our skin vary depending on the amount of sun exposure we have had in our lifetime, our skin type, our age, our genes, and a variety of other factors. Sun damage is cumulative and can take years before it begins to show visible signs. While sun damage may not appear during our youth, it will begin to appear later in life as the effects of sun exposure accumulate.
Photoageing can appear in the form of fine lines, wrinkles, discolouration, and textural changes. These cosmetic effects are often visible on parts of the body that are repeatedly exposed to the sun, particularly the face, lips, neck, décolleté, arms, legs, shoulders, and backs of the hands.

Fine lines and wrinkles
With repeated sun exposure over time, the dermis thickens and becomes less able to retain moisture. The lack of moisture in the skin, in addition to the UVA damage to the skin-supporting collagen and elastin fibers, can lead to the appearance of fine lines and wrinkles, predominantly around the eyes and mouth.

Discolouration
The over-activity of melanocytes (pigmented skin cells) caused by years of sun exposure can cause skin discolouration in the form of brown freckles, solar lentigines (age spots or liver spots), and small white marks. These spots commonly appear on the hands, arms, face, and back.

Textural changes
Sun damage can also lead to textural changes of the skin. Long term sun exposure can cause the epidermis to become thinner and more fragile, making it bruise and tear more easily.

While the epidermis thins with repeated sun exposure, the dermis begins to lose its elasticity, resulting in bumps on areas of the skin that have had the most sun exposure.
In addition to these cosmetic effects, photoageing can also lead to life threatening conditions, such as sun spots and skin cancer.

What is the best way to reduce photoageing?
There are several proactive, preventative measures we can take to reduce photoageing:

  • Wear a minimum SPF 30 broad-spectrum sunscreen that protects against UVA and UVB radiation on areas of the skin that are exposed to the sun every day, particularly in the summer
  • Pay extra attention to protecting the face, ears, lips, neck, décolleté, and hands, the areas most susceptible to photoageing
  • Apply sunscreen to the body liberally and reapply every two hours (or after swimming, excessive sweating or toweling off)
  • Reduce exposure to UV radiation by limiting time in the sun, especially between the peak hours of 10am and 4pm
  • Refer to Environment Canada’s daily UV Index reports and take appropriate precautions based on the predicted UV levels
  • Avoid tanning from the sun, sun beds or indoor tanning equipment, all of which emit harmful UV rays
  • Wear protective clothing to cover exposed skin, such as long-sleeved shirts, long pants, wide-brimmed hats, and sunglasses
  • Seek shade outdoors (when possible) from trees, shade coverings, umbrellas, and buildings

 

References
American Academy of Dermatology
Canadian Dermatology Association
Know Your Own Skin
Skin Cancer Foundation
WebMD: Effects of Ageing on Skin