In order to better understand the mechanics of tanning, let's first talk about the difference between UVA and UVB radiation. Ultra-violet B radiation is a type of solar wave that is more potent than Ultra-violet B radiation because of its greater frequency.
UVB wavelengths have shorter frequencies and thus are more energetic. In other words, there are a lot more coming at you in the same amount of time. Therefore, UVB rays are more potent and harmful than UVA rays. While UVB rays are more likely to cause sunburn, UVA rays are more likely to trigger the body to show an immediate tan. Even though UVA rays are less potent, they can still cause skin aging (wrinkles and sun spots) as well as cancer due to damage to cell DNA.
What is a Tan?
To be blunt, a tan is the body's response to sun damage by UV radiation. There are two types of tanning: immediate darkening(which gives no sun protection) and delayed response (which gives the body a TINY bit of sun protection). Before we discuss this, let's discuss the cells and molecules involved:
Melanocytes are cells that live under the surface dead layers of skin and they produce a pigment called
melanin (not to be confused with melatonin, which helps me fall asleep after too much coffee). Melanin is composed of tiny granuales that are spread out under your dead skin layers to give your skin color.
Side note: melanoma, a highly aggressive skin cancer, is caused by cancerous melanocytes. This is why doctors tell you to look for unsual-looking moles--cancerous melanocytes pump out uneven and crazy amounts of melanin.
Immediate Skin Darkening
Right after UV exposure, the skin redistributes melanin that is already on its surface. No new melanin is made. In addition to this, the body thickens the skin surface (by adding more layers of dead cells) which can cause a dull, leathery look to the skin. Free radicals are also relased, which can cause DNA harm (which leads to cancer).
Delayed Response
This type of tan occurs only after UVB exposure that leads to sunburn. Several days after a sunburn, the body produces melanin and distributes it along the skin's surface. While this tan may last longer than the one caused by UVA radiation, it is at the expense of your DNA. When your skin shows a sunburn, that is a sign of cell/DNA damage. A tan will be the result, but at what expense?
Sometimes, especially with us olive-skinned types, it seems that tans can't be avoided. Understanding the mechanics of a tan will help us understand the dangers of purposly seeking them out via laying out and tanning beds. Our best bet is to layer on the UVA/UVB protection sunblock, put on a long sleeve shirt and try to avoid being outside at high noon.
Remember, tanning isn't healthy, it's our body's way of telling us it's hurt.
She looks happy, but her skin is crying
and she probably looks like this now:
