Why Sun Exposure Is So Important

March 1, 2012 in Categories: by

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An often overlooked component of a paleolithic lifestyle is spending time outside.  While fresh air is invigorating, this is really about getting sun exposure.  Getting enough sun exposure is vital for our health.  You probably already know that our bodies make vitamin D in response to exposure to ultraviolet light.  (Yes, too much exposure to intense ultraviolet light can cause DNA damage in your skin cells and increase your risk of skin cancer, but as long as you aren’t getting sunburns, exposure to ultraviolet light is not only safe, it’s essential for your health.)  Vitamin D is a steroid hormone that controls expression of more than 200 genes and the proteins those genes regulate.  Vitamin D is essential for mineral metabolism (it regulates absorption and transport of calcium, phosphorous and magnesium) and for bone mineralization and growth.  Vitamin D is also crucial for regulating several key components of your immune system, including formation of important anti-oxidants.  Very importantly, Vitamin D has recently been shown to decrease inflammation and may be critical in controlling auto-immune and inflammatory diseases.  Vitamin D is also involved in the biosynthesis of neurotrophic factors, regulating release of such important hormones as serotonin (required not only for mental health but also for healthy digestion!).  Vitamin D helps control cell growth, so it is essential for healing.  Vitamin D also activates areas of the brain responsible for biorhythms.  Scientists continue to discover new ways in which Vitamin D is essential for human health; for example, Vitamin D may prevent cancer. 

Vitamin-D production from ultraviolet light exposure is not the only important aspect of sun exposure.  Cells throughout the body, including the skin and eyes, are sensitive to blue light from the sun, which is strongest in the morning.  When special cells in the retina of the eye are stimulated by sunlight, they directly affect the pituitary gland and the hypothalamus region of the brain.  The hypothalamus is responsible for circadian rhythm (your body’s internal clock) and regulation of hormones and the nervous system.  Proper regulation of circadian rhythm is crucial for quality sleep, stress management, and the cyclic pattern of expression of so many hormones in the body.  One important circadian rhythm hormone, produced by the brain’s pineal gland and regulated by sunlight, is melatonin.  In addition to being critical for quality sleep, melatonin is a powerful antioxidant, is important for intestinal function, and can help prevent depression.  The hypothalamus and the pituitary gland influence the adrenal glands, which control cortisol production.  These important effects on brain activity, which increase alertness, improve cognition, and boost mood and vitality, are all independent of Vitamin-D production.  So, while taking a Vitamin-D3 supplement is very helpful when the sun is scarce in the winter months (or if you do shiftwork or face other challenges to getting out into the sun), it can’t replace the huge range of health benefits of just plain old getting outside. 

How much time should you spend outside? It depends on your personal body chemistry, how much skin is exposed, what time of day it is, what time of year it is, clouds and air quality, and where you live.  Aim for as much as possible (taking care not to get a sunburn!), but at least 15 minutes most days is a good rule of thumb.


I’m curious what you think about tanning for those of us who live in areas where it’s too cold to expose more than our faces during several months of the year.

I think tanning provides the vitamin-D benefits but skips on the responses to other wavelengths. I would suggest a double whammy approach of still getting outside, especially in the morning, just to have the light exposure to help regulate circadian rhythms and then also adding a short tanning session once or twice a week for the bolus of vitamin D.

Thanks so much for your response! I do take a bus to work every morning, so I spend about 10 minutes outside in the morning and usually make the 40 minute walk home every afternoon, but all bundled up. I just signed up with a tanning place yesterday, as I’ve been feeling like I’m missing the sunshine. I’m new to your blog and loving it. Thank you!

Please, please, please wear sunscreen and get the Vit D you need from your diet and/or supplements! Go outside but put on sunscreen and wear protective clothing. The Surgeon General has just classified tanning beds as carcinogenic, so for you to promote these cancer beds as a positive outlet for getting the recommended Vit D is an insult. I am worried that your followers trust your opinions so much that they are actually going to follow what you say and put themselves and those they love at risk for skin cancer and Melanoma (the most deadly form of skin cancer). Do you know that your risk of getting Melanoma increases 75% with just one tanning bed visit?!
I enjoy reading your posts on eating right and how to eat Paleo, but you lost me completely when you began encouraging people to seek out the sun and increase their risk of such a life threatening cancer. Trust me, I’ve had to look my 2 daughters in the eyes and tell them I may not be around in the next year. Stage IV Melanoma patient posting here. I would encourage anyone reading to see a Dermatologist and get their opinions on sun safety prior to doing the recommendations listed in this post. It may just save your life!

What are your thoughts on sunscreen? Obviously we want to protect ourselves from overexposure and sunburns, but does sunscreen also block all of the awesome benefits of sun exposure for our bodies?

I don’t use it personally unless i know I’m going to burn if I don’t. I prefer to just use shade or getting out of the sun to prevent a burn when possible. But, burning is bad, so if I’m going to be on the beach for the whole day, I do use some.

I like this approach also. I work outdoors a lot and if I know I won’t have a lot of shady area I usually try to use sunscreen to mitigate (especially for multiple days of 5-8 hours of exposure). But I do try to get at least my arms exposed without sunscreen to soak up a bit of sun when I know it won’t lead to overexposure.

The largest organ in our body is our skin! Tan skin is damaged skin! Damage is cumulative! Sun block is necessary to prevent damage. The FDA considers a tanning booth equally as damaging as Mustard gas! UVA goes right through glass when you are driving, causing damage and aging.

Can you help explain something with regards to Vitamin K. My understanding is you need K ( K3?) to help move the Vitamin D in your body where it needs to go. Without Vitamin K you will not absorb or use the D as needed. If you are not eating grass fed meats and/or dairy and you are not eating much in K rich vegetables, then is what I understand correct? How much K do you need in ratio to D? Thanks in advance for your help.

Yes you do–K2. If you aren’t getting it from wild fish and grass-fed or pasture-raised meats, the bacteria in your gut can convert the K1 is green veggies into K2. I don’t know what the idea ratio is… best person to pose that question to would be Chris Masterjohn.

With Lupus, I have to avoid all sun exposure. I flare at the least amount. The dark winters of Seattle seem to help. When I started to take D3 supplements, I felt much better. But I still go out in the sun only with sunscreen, hat, longsleeves, even gloves on bright days. There’s no way short of a burka to avoid reflected sunlight from sidewalks. I usually start flaring in April (in Seattle!). In the summer, I can stand in the shade, or indoors with all the doors open, and after the sun goes down and it’s still light out, I can go outside, hatless and in a tank top!!!

I don’t know. I just assumed it was UV. Auto glass is no protection. I don’t know about fluorescent lights; the only time I get a concentrated dose, I feel the dryness (Sjogrens) before any light reaction. Why do you ask?

I’m not sure that guidelines exist for a minimum amount. It’s just really important not to let the baby burn. In the olden days (yes, I use that term loosely), they would keep babies in a bassinet outside for an hour or more, but with blankets draped over the top to create shade. I generally think that the more time outside the better, as long as no one is getting sun burns.

II have seen it written in a couple of places (Dr. Merola article being one) the equivalent of units after being in the sun without sunblock one hour is 20,000. That number against (at least Dr. Mercola’s) the different recommendation of units per day for men, women, children pregnant etc…. is more than satisfactory. As Paleo mom says there are no minimums set per se and this may be due to how we just (last couple of years) have learned our current medical recommended minimums are not even scratching the surface of what we need to be healthy. I just have to also mention, this being our first year eating grass fed/ finished meats and dairy (we are following lacto-paleo) as well more nuts and vegetables, I never” burned”–not even the heat rash I’ve experienced most of my life. I spent every day this summer taking my two year old out to be in the sun sans sunblock and after one hour neither of us burned-just a slight healthy color. I am pregnant so not sure if there are some bonus hormones there, but a comment made by Paleo Parents seems to be happening for us as well in being ok in the sun. My bet is if you are breastfeeding while following Paleo with as much organic and grass fed (grass finished when you can get, your baby willreceive the nutrients they would need to be in the sun for just a little bit (15 minutes even would be like 5,000 units).

And BTW Sarah, I’ve managed to reach Chris Masterjohn and he is helping me on my K questions-even told me what results to ask for my latest blood test. Thank you for pointing me in hi direction!

I have a autoimmune disease called vitiligo. Just got it a few years ago I live in Chicago and my daughter got me on the paleo way 1 year ago. Love the sun it doesn’t love me. Looking forward to your book. Thank you

I was just looking into getting a vitamin D lamp (I live in Ireland), but then read that D supplementation is bad for those that are Th1 dominant, and it can increase IgE…I already have many IgE allergies. What do you think?

My son (who will be 2 in a couple weeks) develops a prickly-looking, slightly bumpy rash when he’s in the sun. Does this mean I should try to keep him covered when in the sun? If you have any links or resources about this condition, I’d appreciate it. He eats an almost completely paleo diet. Thanks!

[…] What health issues are you challenged with?  In my personal experience, most gut health issues will improve dramatically the first couple of weeks on paleo and then continue to improve slowly over the next six months as your gut continues to heal (for more posts on gut health, see here and here).  Issues relating to inflammation typically take longer to show significant improvement depending on how well you are sleeping and managing your stress (typically another month or two).  Remember that for many health issues, you need to address all of the tenants of a paleolithic lifestyle (get good sleep, manage stress, get outside). […]

Unless I missed it somehow, it is a bummer that you didn’t address the cancer issue. As someone who has had, and apparently will continue to struggle with, basal cell carcinoma, I was curious to your take on that.

Jc, look above, I’ve left a comment about skin cancer and sun/tanning bed exposure. As a Stage IV Melanoma patient, you should always wear sunscreen when you go outside and NEVER NEVER NEVER use the tanning bed. It was just classified by the Surgeon General as a carcinogen, making it equally as harmful as cigarettes! You can get your Vit D from your diet.

I think it’s only fair that The Paleo Mom replies to the cancer issue and tanning bed question. She has given advice that some people would regard as extremely irresponsible in this day and age and I think it’s a bit cowardly that she has not come back to answer her critics.

Can we have your thoughts, Paleo Mom, on the tanning bed question please, as I live in a colder climate and have considered using one as a way to get sun exposure but have been frightened by all of the media stories regarding the dangers.

I live in Ireland so only see the Sun once every ten years or so. We had sun last year so will be waiting another nine. 😉

In the winter when living in places where you can’t get enough sun, what do you suggest for supplements and how much. Also for a nursing mom, we are starting to not be able to go out daily as it is getting very cold here. We try to take short walks when we can, but getting difficult to do even in the middle of the day!! Would love to know your suggestions?! We eat a Paleo diet, but feel we might need a little more in winter months.

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