Sunlight is made up of heat rays, light rays and UV rays.
Heat rays (infrared) penetrate the deepest into an organism and are perceived as heat. This promotes circulation.
Light rays (visible rays which we perceive as “sunlight”) enable us to see.
UV rays (short wave light with the highest level of energy) are invisible and are responsible for change processes, e.g. tanning and burning of the skin.
We make a distinction between:
Long wave UVA rays (320 – 400nm) = immediate tanning of the skin
These are responsible for long-term damage to the skin, making it inelastic, reducing its ability to bind moisture and also causing premature aging of the skin with the formation of wrinkles. They penetrate into the connective tissues where they weaken the elastic and collagen fibers. Excessive exposure to sunlight is the most common cause of skin cancer.
Short wave UVB rays (285 – 320nm) = long lasting pigmentation
Excessive exposure to these rays can cause immediate damage to the skin, the first sign of damage being excessive sunburn. They also damage the structure of skin cells.
UVC rays (200 – 285nm)
are of no significance as far as sunbathing is concerned. Because they are absorbed outside the atmosphere, they do not affect people through natural sunlight.