Sunlight lightens hair but darkens skin, why so
- The colour of our skin and hair is determined by a pigment called melanin.
- The concentration of melanin in our skin and hair determine the colour.
- Melanin is produced in skin when exposed to sunlight, hence darkening the skin.
- Hair cannot produce melanin as it is already dead, the melanin present in hair is broken down in a colourless compound by sunlight, making our hair lighter.
If the sunlight lightens one’s hair, why doesn’t it work in the same way to lighten your skin? The colour of your skin, hair and eyes depends on a pigment called melanin. Melanin is produced in the body to protect you from the harmful rays of sun, and every one of us produces melanin in their skin except some people who have a genetic disease called Albinism. However, the concentration of melanin produced in the body gives your skin and hair their characteristic colour. If the concentration of melanin in your skin is less, you will have a light coloured skin and if it’s high you will have a darker toned skin. Same goes for your hair colour, lower concentrations of melanin give light coloured hair and vice versa.
So, why does hair gets lighter, while the skin gets darker in the sun?
The answer is simple. Your skin is alive and your hair is dead. Living cells can produce melanin, however dead cells only store some melanin pigment, and if it is broken down they cannot produce any more.
Darkening of skin in sunlight
The production of melanin in the skin depends on two factors, the first one is genetics, which sets the basic tone of your skin colour. The other factor is exposure to sunlight, which is responsible for giving you a tan, which fades overtime as the melanin is broken down in the skin.
When your skin is exposed to sunlight, the melanocytes or melanin producing cells in your skin start producing more melanin. This is a protective measure taken by your body to block the harmful DNA damaging sun rays. Melanin forms a cover and protects from sun damaged skin. This is why long exposures in sunlight will make your skin darker.
Lighting of hair in sunlight
Hair is made up of dead cells which get their colour through melanin while the hair is still growing. It means that the exposed part of the hair, which is already grown, will never produce any more melanin because the cells are already dead.
Unlike our skin which keeps producing melanin, to replace the pigment, our hair cannot do so. The melanin already present in the hair is broken down by the strong UV rays of the sun. When melanin gets oxidized by these rays, it turns into a colourless compound, hence resulting in lighter coloured hair.
This effect of sunlight on hair is used by people who wish to lighten their hair colour without using chemical bleaches. They use sun hair lighteners which speed up the process of oxidizing melanin in hair.
Image Source: Getty
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Source: Onlymyhealth editorial team Aug 03, 2016
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