It's the end of the summer, and that means tanning season is coming to a close. Why does that tan you so carefully built up disappear?
Quite simply, your tan falls off.
It's not the most comforting phenomenon to think about, but humans are constantly shedding flakes of dead skin cells. Every day, you lose about a million such cells, actually, and some of those are the cells that produce the melanin that makes your skin dark. Known as melanocytes, these cells make up about one percent of your skin cells.
The melanocytes produce excess melanin in the sun because they contain structures that respond to UV light, a component of sunlight that can damage DNA. Melanin protects the nucleus of a cell, which houses DNA, from the harmful rays.
However, after the summer, if you live in a temperate area, there are fewer hours of sunlight during the day. As a result, melanin production slows and the dark skin cells you slough off are replaced with lighter ones. However, don't expect the dust in your house to look any darker as your tan wanes – it's a myth that dust is mostly made up of dead skin.
Photo: twitchery | Flickr