It’s one of those things you probably wonder about for a minute and then never bother to think about again… What IS a tan? How does your body change color like that?
Well, wonder no longer! There are a few different ways your body can tan naturally. The most obvious is, of course, from the sun! Light from the sun reaches earth in three forms: visible light, ultraviolet light, and infrared. That second type, ultraviolet light, is classified into three categories:
1. UVC, which doesn’t affect us because it’s filtered out by the atmosphere before it can get to our skin.
2. UVB, which typically causes damage in the form of sunburn.
3. UVA or black light, which causes tanning.
The problems we associate with sun exposure, such as skin cancer, wrinkles, etc. are mostly caused by harmful UVB rays. Research suggests UVA might have an increasing hand in these things as well, however. Most of the sun’s UV radiation at sea level is of the UVA variety.
UVA can be reflected off of snow or water. Snow actually reflects roughly 90% of UV light, which is why you can get severe sun burns while skiing. Sand reflects up to 20% of UVB too, so at the beach, you’re getting more UV exposure than you would sitting in your backyard. It’s hitting you from above and below! There are certain surfaces that can absorb UV radiation rather than reflect it, such as certain types of glass.
Ultraviolet light in the sun stimulates the production of melanin in our skin. This pigment absorbs UV light, protecting cells from damage. Imagine you put a sponge on top of a piece of paper and slowly dropped beads of water onto it. The sponge would soak the water up before it can ruin the paper. That’s sort of what your melanin does to UV rays. Over time, this protective pigment makes your skin look darker, hence: a tan! Caucasians typically have the least amount of melanin in their skin on a day-to-day basis, but in many other races, there is a continuous melanin production, which causes the skin to remain pigmented and also offers more protection against UV rays on a daily basis.
It’s important to note that all UV rays are potentially dangerous. If you keep dropping water onto that sponge, eventually, it will soak through and damage the paper. That’s fine when we’re talking about metaphorical paper, but not so great when we’re talking about your skin! UV rays can cause deep damage to your cells, which results in painful sunburn at best and fatal skin cancer at worst. It’s important to protect yourself from skin damage by wearing sunscreen when you’re outside. Avoiding direct sunlight is the best way to protect yourself. This really ruins your chance at a tan, though.
There’s one more way that you can get naturally darker skin, however. That’s through DHA. DHA is a non-toxic, organic compound that creates a chemical reaction within the amino acids in the outermost layer of your skin. This reaction does not involve the underlying skin pigmentation, nor does it require exposure to ultraviolet light to initiate the change in color. It is similar to the maillard reaction which occurs in food. It’s a natural, temporary color that looks just like a tan that occurs from melanin. The active ingredient in airbrush tanning is DHA. The color produced in an airbrush tan typically lasts 7-10 days, but it is much safer than roasting yourself in the sun or using a tanning bed.