Collagen is the main type of protein found in the mammalian body, and is primarily a structural protein found between cells and in joints. Skin, tendons and ligaments make up the majority of collagen deposits in the body.
When skin cells are stressed (from cold weather, bad diet, general ageing etc.) they tend to overproduce collagen, similar to the process of scar formation and fibrosis, which leads to an inflammatory response characterised by excess collagen framework and thus a reduction in active healthy cells.
The overproduction of collagen, combined with a stressed/inflamed state ultimately results in tough and wrinkly skin. This slow, ageing process can be seen more clearly in animals; older animals typically have thicker, harder hides and meat from older animals is typically tougher (due to more collagen framework in the muscle meat).
Collagen exists in a balance within the skin, with an equilibrium between the production and break down of the protein (to allow for tissue growth, remodelling, etc.). Too much collagen production and you get wrinkly, tough skin and eventually fibrosis.
Too much collagen break down (such as from various invasive cancers) and you destroy the extracellular matrix which is needed for normal cell function.
HOW DOES RED LIGHT THERAPY IMPROVE THE SKIN?
Wrinkles and aged skin are formed slower than scar tissue, but by the same essential process – an overproduction of the collagen framework and so a lack of metabolically active cells. How does red light prevent this?