Yesterday at the gym I saw the most amazing looking guy – a hot blonde, six foot-ish, phenomenal body, gorgeous blue eyes and the hottest smile ever. He also had a perfect little tan. Nothing crazy dark (he totes wasn’t orange) – it looked like he went somewhere tropical for the holidays.
[Picture me drooling at my desk thinking about him right now]
Anyhow… in addition to a lot of other things going on in my head, he made me think about going tanning. I got to thinking about it today at work and figured I would tell you how you tan.
In the bottom layer of your skin (science term: the stratum basale of the epidermis) there are some cells called melanocytes. Melanocytes produce melanin, a lovely dark substance that is able to absorb UV light from the sun or tanning bed. By absorbing the UV light, melanin protects your body (mainly your DNA) from UV damage. The melanin building up in your skin is what provides you with your tan. The darker your tan, the more melanin your body released.
Right there is a great science fact if you think about it for a second. A basic principle of evolution is that an organism will not waste energy doing something unless it’s beneficial. A tan that looks super cute is not helpful to your body. Your body producing a tan to protect itself is very helpful. The more sun you get, the darker you get, because the more protection you need. I really do think the human body is amazing! If nothing else comes out of this blog, I hope you appreciate science and your body a little more now too.
But you may ask: how does your body know to make melanin? The pituitary gland in your head is tied to the optic nerve. When you go outside into the sun and expose your eyes to UV light, the pituitary gland starts producing a hormone (Melanocyte-stimulating hormone (MSH)) that circulates through the blood stream. When MSH reaches the melanocytes, it tells them to start producing melanin (thus the name, MSH). Then you will start tanning. This whole process takes a little time and that is why you don’t start tanning right away. For some people (myself included) the tan will not appear for a few hours, or even until the next day.
Since MSH is needed to tan and in order to get it produced you must expose your eyes to UV light, you shouldn’t wear sunglasses when you want to tan. Some research has found wearing glasses may actually make you more susceptible to sunburns. Sunburns are a different story and I don’t feel like getting into that today.
And obviously this process is different in everyone. People with naturally darker complexions always have a higher melanin concentration. Yet no matter what color, everyone has basically the same number of melanocytes. Fun.
So there you go. And I am totes not advocating tanning. Melanin is great and all, but cancer is still a major risk. Egh, whatever, I’ll be in a tanning bed soon…
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