Why does hair lighten in the Sun?
If melanin causes the colour of our skin and our hair why does our skin go dark and our hair go light in the sun?
Ben - This is basically because hair is dead. Once it comes out of you, once it's grown, all the melanin it will ever have has already been put into it. It gets broken down by the sun but in your skin the melanin gets replaced when melanocytes put new melanin into your skin.