The ‘Dark Side’ of the Sun

hammock picture march newsletter

Planning a vacation in the sun? You may want sunscreen long after the sun has gone down

Rolling off the press study ups the ante of the dangers of the sun. Researchers from Yale University School of Medicine published a February 2015 study in the Journal Science of UV lights’ damaging effect on our skin that occurs hours after we have been exposed- even in the dark.

Here is what we already have known about the sun’s rays: The sun emits UVA, UVB and UVC light in wavelengths that are not visible to the naked eye. UVA light, at 320-400 nanometers, is the longest in length and reaches the earth easily. It makes up 95% of the sun’s rays that we absorb. It can penetrate glass and clouds as well as our skin and is classified as a ‘human carcinogen’. With enough exposure, it can damage the skin’s DNA at a cellular level causing photo-aging, wrinkling of the skin and the initiation of skin cancers. UVB rays, range from 290-320nm, cause the redness in the skin or the ‘sunburn’ we feel and see and damages the superficial layers of the skin. UVC does not reach the earth and is instead absorbed by the ozone layer.

Melanin, our skin pigment made by cells known as melanocytes, has been thought of in the past as the most important photo protective factor of the sun’s UV rays, with the darker the pigment the better. However, after sun exposure or UVA light from tanning beds, the DNA in the Melanocytes that produce the melanin can be damaged.

A team of dermatology and radiology Researchers from Yale School of Medicine exposed mouse and human Melanocyte cells to harmful UV rays. The UV light caused a type of DNA damage in the cells known as a cyclobutane dimer (CPD) by causing 2 letters of DNA to bend so that it was unable to be correctly read and therefore, damaging the DNA. The researchers found that the Melanocytes not only generated CPD’s as soon as they were exposed to UV light, but surprisingly continued to generate CPD’s for hours after exposure in the dark. Why in the dark? In the dark the Yale team found two enzymes that stimulated electrons in the Melanin in a slow process known as chemiexcitation. This caused the transfer of energy to the DNA creating DNA damage in the dark that was the same as in the daylight.

The researchers concluded, with melanocytes much of the damage to the skin by ultraviolet rays occurs in the dark long after you have gotten out of the sun.

“I know, I know,” you’re thinking, “I’m going to say the moral of the story is to never lay in the sun.”

Well, yes, of course I’m going to tell you that. But I’m also going to tell you to get ahead of the curve on this; it looks like the market has just opened up for an ‘Apres-Sun’ sunscreen to be applied in the dark. Any takers out there?

http://www.sciencedaily.com/releases/2015/02/150219144641.htm

http://www.zmescience.com/medicine/skin-gets-damaged-by-uv-dark-042423/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/

http://www.cbsnews.com/news/sun-damage-to-skin-continues-after-dark/

http://news.yale.edu/2015/02/19/sunlight-continues-damage-skin-dark

http://www.sciencemag.org/content/347/6224/842.abstract

http://www.skincancer.org/prevention/uva-and-uvb/understanding-uva-and-uvb

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