Seeing the Light: Why Sun Exposure May Be Good for Your Eyes
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.
Then she points toward the epidemiology exploring the link between time spent outdoors and myopia prevention, which is much stronger. Let’s take a look at a few studies:
In Chinese school children, myopia progression was inversely correlated with outdoor activity.
Near work (studying, reading) did not correlate with myopia progression, but American kids who played fewer sports outdoors had more myopia.
In Taiwanese rural children, outdoor activities might be “an important protecting factor for myopia.”
In teens from Singapore, outdoor activity appeared to protect against myopia progression.
Parental myopia status interacts with risk, too, though. In one study, kids with two myopic parents were at the greatest risk of developing myopia themselves, more so if they did not engage in outdoor sports. Kids with no myopic parents and who played a lot of sports outside had the lowest risk. Genetic predisposition expressed by an environmental trigger, anyone?
Of course, any good Primal thinker knows that epidemiology, like Grok logic, only goes so far. It’s certainly interesting, and it can inspire new avenues of inquiry, but science cannot live on epidemiology alone. You need something else to look into, like perhaps a physiological mechanism. Rose’s proposed mechanism was retinal dopamine, a “known stimulator of eye growth whose release is stimulated by light.” A lack of retinal dopamine – from avoiding the outdoors – means excessive eye growth. This is bad, for the eye is a delicate, extremely complex structure with many components, and a lot can go wrong if those components grow faster and bigger than they’re supposed to grow. Like the progression of myopia, which is characterized by excessive eye growth.
But wait – isn’t excessive amounts of light one of the big issues with modern living? Even if we stay indoors most of the day working, browsing, or watching TV, we’re still parked in front of a screen beaming light into our eyes and we’re still immersed in artificial overhead lighting. If all that light is enough to disrupt our circadian rhythms and ruin our sleep patterns, why isn’t it enough to stimulate retinal dopamine release?
It’s the magnitude. Try looking up at the sun in the afternoon. I mean really give it a good, long look. You can’t do it (in fact, that is definitely bad for your eyesight!) for more than a second or two, tops. If you squint, you might make three. Now try the same with an illuminated lightbulb. It’s easy and nearly painless. It doesn’t compare. To quantify the massive gulf between sunlight and artificial light, let’s look at another study. Researchers trying to study the link between light exposure and myopia exposed chicks to various amounts of light. Normal laboratory lighting was 500 lux, “intense” laboratory lighting was 15,000 lux, and sunlight was 30,000 lux. Only intense lab light and sunlight were able to retard the development of myopia, while normal lab lighting – which is still quite bright and very similar to standard office lighting conditions – did not adequately protect. Oh, and good news for you sunglass wearers: the chicks who were continuously exposed to bright lighting while wearing “translucent diffusers” also showed resistance to eye lengthening and myopia.
To get an idea of how many lux you can expect to “get” in various situations, check out the Wikipedia article on the subject. Prepare to marvel at the insane brightness of the outdoors and the comparatively piddling illumination found indoors. Note that direct sunlight is ridiculously bright (up to 130,000 lux), while just being outside in “full daylight” will provide plenty of light for your retinal dopamine labs. No need to stare at the sun or avoid dark forests. Just be outdoors and the sun will take care of the rest. If you can see stuff, that means light is getting to your eyes, it’s from the sun (and thus bright enough) and you’re good to go.
Of course, us oldsters might be too far gone for sunlight to have an effect on nearsightedness. Myopia develops early (hence the inclusion of 12 year-olds in myopia statistics), so it’s absolutely crucial that kids get plenty of time outdoors. I’d say “as much as possible,” but if you want a specific number, Kathryn Rose suggests between 10-14 hours a week as a bare minimum. Barring that, I suppose you could blast your toddler in the face with a halogen bulb every couple hours. No, but really: let those kids get outside, get dirty, play with bugs, climb stuff, and get some sun. Although the chick study showed that sunglasses may not be problematic, I don’t think kids need ‘em, and they might still interfere with normal eye development. They’d just fall off, anyway, unless you hooked the kid up with some Horace Grant-style goggles.
Given all that, I think it’s safe to say that sunlight exposure probably plays a role in the development of nearsightedness. It’s not the only player – physiology is rarely that simple – but it appears to be a major factor. Anyway, I think we’ll have a better idea in the coming years. My Pubmed trawling pulled up a ton of very recent studies on the subject, all in the last few years or so, so we can probably expect more definitive answers in the near future.
Are you nearsighted? Did you play a lot outdoors as a kid? What’s your family history of myopia – do your parents have it too? Let me know in the comment section!
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Posted By: Mark Sisson
“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.”
I’m wondering more about this; I’m from the norhtern part of Sweden, above the arctic circle, and how do you explain the circadian rhythms in our part of the world? In summer, there’s sunlight all the time, and in the winter we ha approx 2 hours a day with sunlight, everything else is dark.
Apart from this question, I also wonder what you think of lazer eye surgery? I had myopia, like everyone else in my family (mom, dad, 3 siblings), but had surgery in january. Yes, everything matches our family – practically no outdoor playing when we were little, so I think you (and studies/research) are spot on. But eye surgery isn’t really grok logic, and how do you think it effects other parts of the body?
I’m just trying to se things the same way as you do – evolution came first.
Plese do not listen to Mr. Sisson’s misguided advice. Unfiltered sunlight and vitamin D may be beneficial for the skin, but not for the eyes. You may develop growths on the surface of your eyes called pterygia (surfers get them) early in life. Later, cataracts develop sooner and after a certain age, unfiltered sunlight (particularly the UV-blue spectrum) will accelerate aging in the back of your eyes. Mr. Sisson is confused and cannot discriminate between sunlight for skin and for eyes. Yes, play outdoors, natural vitamin D is essential for life. But your babies should be given sunglasses.
When I was 15 they told me I needed glasses. But I knew about muscles and that the eye is focused by muscles.
I knew that if I wore glasses those muscles would get weaker. Would your legs get stronger if you started using a walker?
So I ignored them. I never wore glasses. I had 20/30 vision at the time. Now I am 40 and have 20/20 vision.
The whole glasses thing is a scam, plain and simple, because after you weaken your eyes with glasses, a few years later you end up needing…..yes! a new prescription! And how much are those lenses? How much are those frames? We can put the computing power of a 1960s supercomputer in your pocket for under 500 dollars but hey those glasses that you need are so simple, very old technology, and way overpriced. Glasses – especially on the young – will be known in the future (if the same people who control the world now are NOT in control then)as one of the “great lies”.
Do the eyelashes on the eye of this picture have mascara on them? If so that’s a coincidence because I just discovered that mascara makes my eyes very dry. I guess I already have problems with dry eye and it makes it worse. I never wore mascara until recently, because I have dark lashes anyway. I usually only wear in on an occasion. I had no problem with dry eye for a few weeks. Then a date night with husband proved that something in my mascara is making my eyes dry! Waste of money and time anyway, so into the garbage it went!
If sunlight hurts your eyes, wear sunglasses. Grok would have, if there ever was such a figment of Mark’s imagination. The first thing I do when I walk outside on a sunny day is sneeze.
Besides, hasn’t anyone ever seen what the Eskimos used to wear to prevent snowblindness? A type of primitive sunglasses.
Grok is a crock.
I had painful dry eye syndrom and it was progressing toward sjogren’s syndrom and nothing the doctors gave me helped at all. Once I switched to primal lifestyle, it went away. They are both a result of INFLAMMATION due to grain and HFCS. My guess is that myopia is also caused by inflammation/non-primal diet.
Eight yrs ago I was about to get a lip biopsy to test for Sjogren’s Syndrome. I cancelled the test as I started to salivate and tear as soon as I stopped eating gluten. Two years ago I transitioned to a primal lifestyle. I am not myopic but I did have one sister with high myopia.
HOW to improve vision NATURALLY?
Improper vision habits and mental stress causes eye muscles to deform. Light is therefore unable to focus properly on to the retina causing vision problems such as myopia and astigmatism.
There`s a natural method for regaining perfect vision without contacts or glasses called: THE BATES METHOD. It teaches you relaxation techniques such as palming, breathing and other healthy vision habits.
Just learn to let go and let your eyes do their thing.
Here are 15 more articles on Vitamin D and UV and vision related diseases
http://www.vitamindwiki.com/tiki-browse_categories.php?parentId=70&sort_mode=created_desc
Mark,
I practically lived outside as a kid. Football was definitely a year round sport as a kid.
I had no issues with my eye sight until I started using computers, which was my early teens. As you can expect, I am nearsighted. My uncle, 13 years older than me, also started needing glasses for distance right at the same time, which is when he started using computers more.
I don’t know about you, but my n=2 study says computers are what made me nearsighted.
played outside constantly as a child. am over 50 now and just barely myopic …just starting really…and not bad, noticing a difference on highways, but again, minor.
Dang it, Mark! My girlfriend already thinks I’m weird for all the primal living I do. I don’t know what she’s going to say when she finds out I don’t wear sunglasses anymore. But, as a sciency type of guy, I can’t refute the data.
No shades at the beach tomorrow!
Reading the study on Children of Chinese Origin Living in Singapore and Sydney, I was wondering if the reason for Myopia could also partly be the amount of chronic stress. The children that play more outside, may also be the ones who experience less stress. That may also explain why so many frustrated CNN commenters claim to have been outside a lot, but still myopic.
I stumbled upon a paleo article on myopia published in 2002, which cites studies that hunter-gatherers hard had any myopia.
Without glasses I can see clearly at 5 inches from my nose, but I was very much an outdoor child. However I agree with the hypothesis. I feel humans were never intended to be indoors away from the sun as much as we generally are now.
My mother’s nearsightedness and my father’s astigmatism gathered in my eyes.
There must be a moderate amount that does the trick, because I was raised in the pre-give-a-crap-about about sun exposure, or fancy sunblock lotion era and was told daily to stay outside until the sun went down my whole childhood. Those massive amounts of early childhood sun exposure didn’t negate my nearsightedness in the least… all the better to check out my extensive sunburn scarring, I say!
I had 20/10 vision as a child, up through junior high, while living in a small mountain town, where even the junior high and early high school kids played outside a ton: skateboarding & tubing the river in summer, snowboarding & sledding in winter, bikes all year ’round, small game hunting, you name it. 12-14 hours a week outside? Heck, it was 12-14 hours a day for a lot of us, at least in summer & on weekends. And I was doing a lot of reading throughout this time, I was an avid reader of newspaper & books since elementary school. So no, near-point accommodation was not the factor here.
So when did my vision slide to 20/20 in one eye & 20/40 in the other? In junior year of high school, when I got a car, and quit skateboarding & biking everywhere. I did spend a lot of time outside after that, but.. it was after dark, and a keg was usually involved. And that’s a whole ‘nother ball of wax, you see.
So, there you have it, another n=1 anecdotal story that fits the data very well.
Epilogue: I’ve had good success in improving my eyesight in both eyes since then, now about 20/15 in the left and 20/25 in the right. It changes a lot though. My eye exercise & nutrition regimen was to eat a lot of beta carotene-rich foods, do some exercises for accomodation & focus, and slowly
decrease my prescription with the help of my optician, who slowly ground down my prescription until it was not needed. Even for visually demanding activities like hunting, I can now hunt & shoot a gun very accurately at 100+ yards, no correction needed, and a compound bow to 60+ yards. This is great, because no glasses or contacts are ever as good as a bare eye in low light conditions.
It would be great to see a post on Grok’s eye exercises!
does anyone know if sunlight can work wonder for presbyopia as well? ^_^
(Lady Grok does not like reading glasses!)
Hey,
I am short sighted. Played a lot outdoors as a kid but both parents short-sighted too. Genetics won this round I reckon Developed it in late-teens/early 20s.
I was an extremely active kid who was *always* outside and was still in glasses by 12 years old.
Perhaps kids play fewer outside sports due to the onset of myopia which makes it more difficult to excel at physical activities?
So to state the obvious, we know that there must be genetic predisposition. Clearly, some people are luckily not susceptible to myopia no matter how much indoor reading or junk-food eating they do. My theory: For those with the “bad” genes (which express themselves through a weakened sclera or accomodative lag or both, but especially the latter), I believe myopia begins with so-called “pseudo-myopia” caused by “accomodative spasm” (lens remains in focused state) after prolonged near work. But contrary to what is commonly theorized, this in itself does not cause axial elongation of the eye and permanent elongation through increased intra-ocular pressure. If anything, I would think the spasm would PREVENT further nearsightedness because any blur on the retina at that point would be myopic blur and under this condition the eye stops growing. However, glasses move the focal plane back to the retina and at this point no amount of focus (accomodation) will bring the closest objects into focus since the lens was already focusing to some degree during the fitting of the glasses and further focusing is beyond its range. Therefore, the only way for the eye to regain emmetropia is through axial elongation, and this is where the retinal defocus pathways come into play. I have read that cycloplegic refraction is not guaranteed to eliminate the spasm to allow for measurement of the true prescription (which indicates that the “spasm” is not so much a ciliary muscle (lens muscle) spasm as it is a condition of the lens retaining its shape after the near-work), so my theory is feasible even under those conditions. So from there on out, most of the myopia increases are probably due to further axial elongation. It’s possible that the lens also changes more and more over time but it has no muscle acting on it to thicken it (it thickens when the ciliary muscle relaxes). I have read convincing arguments that the lens can be shaped through vitreous fluid pressure during focusing, but it is indisputable that myopic eyes are on average longer than emmetropic eyes, so I think it’s safe to say that elongation is a main factor. Anyway, by moving the focal plane back, you are back at square one and near-work again causes a lot of retinal defocus which leads to even more axial elongation (and possible lens thickening, according to some). How many diopters you will max out at is a function of how strong your sclera is, so both the onset and the limit of myopia is genetic, but the progression itself I believe to be caused by the “treatment” which is glasses. The actual RATE of progression is where nutrition, near-work, ad other environmental factors come into play.
I have two brothers. One got glasses at the same age I did and progressed to near-severe myopia just like me within a matter of years. One refused to wear glasses and never progressed beyond 20/40. There are other stories describing the same thing right here on this site. You be the judge. Nutrition (and by extension sunlight) plays a role in lense and scleral structure and is a contributing factor in the rate of progression, but I can guarantee you that if you put -3.00 glasses on 100 different people, each with different diets (some “primal”, some high-carb), they’ll all end up as -3.00 myopes sooner or later. The high-carb, book-worm, basement-dwelling types might beat the rest to the prescription, but they’ll all get there. They tested this on monkeys and they all got nearsighted to -3.00. Note that my argument is not applicable to those with congenital conditions that caused myopia. Also, I believe they have already compared incidences of myopia between countries at different latitudes and concluded that the varying amounts of sunlight did not have a statistically significant effect. (Also, it is common knowledge among the scientists that Eskimos have a very low incidence of myopia).
I just heard a report on the BBC, which lead me to Google, which lead me here.
It seems the correlation between exposure to outside light and myopia is becoming well recognised. The report was about the results of a study, the aim of which was to try to understand the high rates of myopia in Asia and SE Asia. Too much indoors time, studying, napping during daylight time and more study at night. Singapore (where I am) was of special interest because of the racial mix. All races are being affected equally, because the lifestyle (study patterns in particular) are identical for all races here.
My daughter is myopic and getting worse. I’m going outside.