What is sunlight - and how does it affect the skin

The sun is the backbone of all energy and therefore provides many benefits, from supporting photosynthetic life to producing vitamin D in humans. However, as with most biological processes, there is a balance; While sun exposure is good, there is a limit and overexposure can be harmful, especially for the skin.

What is sunlight?

Sunlight consists of a spectrum of rays of various wavelengths. Visible light has a wavelength of 400 to 700 nm, while invisible ultraviolet (UV) light has a shorter wavelength (280 to 400 nm) and invisible infrared light has a longer wavelength (700 nm to 1mm) ... Longer wavelengths of visible light and infrared light can penetrate deep into the skin, although they are less likely to cause damage.

Short-wave ultraviolet light that interacts with skin cells generates highly active free radicals.

These excess free radicals (oxygen molecules) cause cell damage. The more damage they do, the greater the likelihood of wrinkles, chronic diseases, and other conditions, including skin cancer.

Oxidative stress is produced by an disparity between the production of free radicals and the body's ability to neutralize them with antioxidants. Since UV light has a short wavelength, it can only penetrate through the stratum corneum, epidermis, and dermis (upper layers), but not through the hypodermis (lower layer), although it can cause a number of complications in these tissues. ...

Learn more about the structure of the skin.

There are three types of ultraviolet light: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC):

• Although UV-B radiation provides the energy the skin needs to produce vitamin D, it also causes sunburn and direct DNA damage.

• UVA rays also contribute to skin damage, especially premature aging.

UVC rays are blocked by the earth's sky and therefore do not reach the skin. UV rays

The amount of UV light that reaches the skin depends on several factors, including the time of day, season, altitude, and geographic location. During periods of intense UV radiation, such as midday or on a hot summer day, it is recommended to wear protective clothing and sunscreen when going out.