There are two main processes by which the skin ages. One is called intrinsic and it is due to chronological and genetic factors, i.e the passage of time and genetics. The other is called extrinsic and is due to environmental and lifestyle factors, such as sun exposure and smoking. If we take a thin slice of intrinsically and extrinsically aged skin and examine them under the microscope, they will look quite different. These structural differences seen at the microscopic level, translate into different appearances of the skin to the naked eye. Intrinsically aged skin appears thinner and finely wrinkled, while extrinsically aged skin has a leathery, coarse-wrinkled appearance.
This photograph, which first appeared in the New England Journal of Medicine, is of a 66 year old truck driver whose left side of the face was exposed to the sun through the side window of his lorry for 28 years. The intrinsically aged right side of his face is in stark contrast to the left side which has been ravaged by extrinsic ageing due to sunlight. This type of ageing is also called photoageing.
So, what can we do about it?
Sadly, despite the numerous mentions of the fountain of youth in folklore history, its exact location remains to this date unknown. This makes intrinsic ageing from getting older difficult to reverse. As for the genetic factors, choosing one's parents carefully is highly recommended.
Thankfully, there are steps we can take to protect ourselves from extrinsic ageing.
Sunlight is the number one factor contributing to extrinsic ageing. This is because it emits two types of electromagnetic radiation, UVA and UVB, which are capable of penetrating the skin and altering its structure. UVB penetrates superficially into the skin causing sunburns, while UVA penetrates more deeply causing photoageing. Therefore, shielding ourselves from the harmful effects of sunlight is imperative. Sunscreen with a broad spectrum protection against UVA and UVB can ward off the harmful effects of UV light, as long as it is worn correctly. This means applying 15mins before sun exposure and re-applying every 2 hours, or immediately after rubbing the skin or coming into contact with water. It is important to note that going out on a cloudy day or staying under a shade, does not negate the need to wear sunscreen as UV rays can reflect off clouds and other surfaces. UVA can also pass through glass.
A more inexpensive option of course is to move into a cave and never venture out again.