Skin tans primarily due to exposure to ultraviolet (UV) radiation from the sun or artificial sources. When UV rays penetrate the skin, they trigger a protective response that leads to tanning.
How Tanning Happens
- UVA radiation penetrates deep into the lower layers of the epidermis and stimulates cells called melanocytes to produce melanin, the brown pigment responsible for tanning. This process darkens the skin as melanin absorbs UV radiation to protect skin cells from damage
- UVB radiation affects the upper layers of the skin and causes direct DNA damage. In response, the body increases melanin production (melanogenesis), which leads to delayed but longer-lasting tanning that also provides some protection against sunburn
- The initial darkening from UVA exposure is mostly due to oxidation and redistribution of existing melanin, causing rapid but temporary skin darkening without significantly increasing melanin production
- Increased melanin accumulates in skin cells, acting like an umbrella over the cell nucleus to block UV rays and prevent further damage
Summary of the Causes of Skin Tanning
- Exposure to UVA and UVB rays from sunlight or tanning lamps.
- Activation of melanocytes to produce more melanin pigment.
- Oxidation of existing melanin by UVA rays.
- DNA damage from UVB rays triggers increased melanin synthesis.
- Skin type and natural melanin levels influence tanning ability; darker-skinned individuals produce more melanin and tan more deeply
Thus, tanning is the skin’s natural defense mechanism to protect itself from UV-induced injury by increasing melanin production and darkening the skin
