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But what exactly is a tan? How does our skin get this tanned complexion? Zoom on the holy grail of summer!
Mechanisms of tanning
As we saw in the previous article on the skin, it is made up of an epidermis (superficial) and a dermis (deep layer). It is the cells of the epidermis that tan. In the epidermis, there are specialized cells at the origin of our tan: the melanocytes. Under the effect of UV rays, cells will increase the production of a colored pigment: melanin . The capture of UV by melanin (which will oxidize) allows radiation to be stopped in its progression and therefore to protect the deep and fragile layers of the skin . Subsequently, the melanin is expelled by the melanocytes and will color the neighboring cells of the epidermis, at the origin of our pigmentation.
There are two types of UV in solar radiation:
UVA : they cause rapid pigmentation (of the order of a minute) but will also disappear quickly. It is therefore not really this type of radiation responsible for tanning but makes it possible to obtain an "evening tan". This radiation burns little (1000 times less than UVB).
UVB rays : they are responsible for our famous tan. It will appear about two days after our exposure to the sun peaking around the 20th day then gradually disappear if no other exposure appears.
Unfortunately, the rays that produce the tan are also the ones that burn the most. UVB burns 1000 times more than UVA rays, and makes 1000 times more tan.
Why does the tan disappear?
Since the tan is located on the cells, the keratinocytes, of the epidermis and these are renewed every thirty days or so, it will naturally and gradually disappear. Indeed, one month after the last rays of the sun, the skin will be totally regenerated and therefore, there will be no more traces of tanning.
Be careful, however, the fact that the cells take a month to renew themselves does not mean that the tan necessarily remains for a month. Indeed, the fact of peeling will make the tan disappear more quickly and conversely, a well hydrated skin will prolong this tan.
Sunburn and easy to tan? What are the differences depending on the type of skin?
And yes, fair and dark skin tones are not going to have the same tendency to tan and sunburn. But what are these differences related to? Each individual, depending on their genetics, will produce more or less melanin, therefore making a difference in the way they tan.
For very fair skin, the majority of the skin will produce red pigments: the phéomélanine, which does not protect against sunlight. Conversely, dark skin will have a majority of brown pigment, theeumelanin which effectively protects against radiation.
Be careful, however, for dark skin, this is only partial protection, so always make sure to use protection suitable for exposure.
There you go, you know all the secrets of tanning!
