Melanin: Coloring in the Human Body

Though it might seem relaxing, lying in the sun ignites a flurry of activity in your skin. Read on to find out about the biological process that results in a tan.

When sunlight hits your skin, it sets off a chain reaction that might end in a bronze tan or blistering sunburn, depending on a number of factors. At the top of the chain is the UV radiation itself, which hits the surface of the skin and stimulates melanin-producing skin cells called melanocytes. There are actually three types of melanin: eumelanin, pheomelanin, and neuromelanin. The first two contribute to hair, skin, and eye colour, whereas the third resides in certain parts of the brain (where its function remains something of a mystery to medicine). Eumelanin shows up as a brown colour, while phaelomelanin results in a red hue. (Blondes and redheads produce more phaelomelanin and thus tend to tan poorly.)

Melanin isn’t just there for looks. It acts as the skin's shield, designed to absorb UV radiation and quarantine its destructive effects from reaching other cells. Lighter-complexioned people produce melanin when subjected to UV rays over a period of time, which is why it often takes multiple sessions in a tanning bed to get a tan. Those with darker complexions—and the same number of melanocytes, curiously—produce melanin on a regular basis regardless of sun exposure, lending their skin a much more effective defense against skin cancer.