How does the your skin color achieved by tanning fade overtime?

I%26#039;m talking about indoor tanning. I tanned last summer (indoor tanning on the beds) about 5 sessions and I got a really nice deep color. The color lasted a while a couple of months but after time it gradually faded and eventually I%26#039;m back to my normal original color I was wondering HOW and WHY does the color fade?|||Whether it be indoor or outdoor, the mechanism by which a person tans proceeds is the same. Those tanning beds which you lay in emit UVB rays, as does the sun, stimulating melanocytes to produce melanin, the brown pigment you see. This process occurs because UVB rays are harmful to the cell, in particular, inducing mutations within the DNA. In order to protect the cells, melanocytes produce melanin in response to UVB exposure. Melanin in turns absorbs the UVB light and thus protects the underlying cells from damage. This process of melanin production continues so long as you are exposed to those harmful rays. When the rays are absent or decreased, so does your melanin production. This occurs because making melanin costs energy. If there is no UVB light, then there is no need for you to produce the protective barrier.





In latitudes above and below the equator, the ray of the sun is not as able to penetrate the surface of the earth compared to areas along the equator. Also during the summer time where earth is closest to the sun, the rays are more intense and has the ability to penetrate to the surface above and below the equator. During the winter season when earth is furthest away, the sun%26#039;s rays are less intense and are not able to stimulate melanin production as compared to the summer season. Hence people tend to get lighter skin/have lighter skin in areas above and below the equator and during winter vs summer.