Seeing the Light: Why Sun Exposure May Be Good for Your Eyesby
Mark Sisson Recently by Mark Sisson: A Guide to Crustaceans, Bivalves and Molluscs, or Why You Should Be Eating Exoskeleton-Bearing Aquatic Invertebrates
Having immersed myself in all things Primal for so long, I find myself viewing nearly everything through the prism of human evolution. Is this food, activity, environmental stimulus, or social more an evolutionary novelty? If so, might it possibly conflict with or impede our pursuit of good health? Is it benign? An improvement, even? Grok logic will only get you so far. It'll give you a nudge in the right direction that is, headed straight to honest inquiry and further research but it's not enough. You shouldn't rest on your laurels if Grok logic suggests what you're doing is right, and you shouldn't make big changes just because Grok logic suggests you're doing something wrong. Instead, use those insights to generate hypotheses, then try to explore them. Research, read, ask more questions. At least, that's what I try to do. It's awfully tempting to just go with conjecture (especially if it turns out to be right on a fairly regular basis!). That little preamble was just my way of setting up yet another question with roots in evolutionary conjecture: does the avoidance of sunlight via indoor living, sunglasses, and general heliophobia have an impact on eyesight, and more specifically nearsightnedness? Going purely by Grok logic and what we know about sunlight's interaction with other aspects of our health, I think it's a reasonable question. To whit: Sunlight and skin Sunlight exposure is required for vitamin D synthesis. When UVB hits our exposed skin, vitamin D is synthesized and distributed throughout our body. Vitamin D is an essential pro-hormone, necessary for musculoskeletal health, immune system robustness, as well as protection from heart disease and cancer. Sunlight and circadian rhythm We need exposure to light at certain times of the day in order to regulate our circadian rhythms. Without daytime/morning light, or with too much evening light, our internal clocks and general health go awry.
Given those two extremely basic, widely-accepted interactions between sunlight and our bodies, coupled with the fact that the eye's express function is to interact directly with light, I think Grok logic regarding the sun and our eye health might be onto something. But we can't be sure, remember, without confirming through other sources. So let's look into those other sources. I'm sure you've heard of myopia. You may have it yourself or know someone who does. In case you don't, myopia is nearsightedness, which is characterized by blurry vision when looking at distant objects. If it weren't so easily countered with prescription eyeglasses, myopia would probably be classified as a public health epidemic. It's that common, and it's getting worse. In fact, the latest statistics indicate that 41.6% of Americans aged 12-54 suffer from myopia, way up from 25% in the early 1970s. That's an awfully big percentage of the tribe that can't throw a spear, shoot an arrow, spot prey, or see the enemy coming from afar. That's a ton of squinters who require assistance. In other words, if myopia were just an unfortunate part of growing old (to the ripe old age of 12!), we probably wouldn't have made it this long. No, there's probably an environmental component to the rise of myopia. Genetics could play a part in determining susceptibility to myopia, and probably do, but an environmental factor is likely to be a trigger for the "myopia gene's" expression. Could sunlight be just such an environmental factor? Kathryn Rose, a visual disorder researcher, thinks so. First, she points to the weak or inconsistent epidemiology that attempts to link time spent on the computer, watching television, reading, and studying to the development of myopia, instead suggesting that the real problem is lack of sunlight. In cases where digital media usage or inside work appears to be associated with myopia, Rose thinks it's actually a measure of displaced outdoor time. June 29, 2011 Copyright © 2011 Mark's Daily Apple
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