Why Kids Need the Sun

Sun LightThis is a guest post from Michelle Fitzpatrick of Happy Paleo Kids. Michelle has worked with special needs children and their families for over 13 years to promote development and mental health. She adopted a “Paleo Diet” to lose weight after baby number 3, and quickly saw that the benefits of eating nutrient-rich, plant-and-animal-based foods would benefit her entire family. After applying the Paleo Philosophy to her family, she felt compelled to find a way to bring the science behind how food impacts child development to the masses. Follow her blog or keep up to date on Facebook, Twitter, and Instagram.

Yes! It’s summer! School is out, the sun is shining, and the kids are… glued to the iPad? I hope not. Summer is time for busy kids to catch up on things they don’t have time for during the school year (like play). Most importantly, it is a time when days are long and the sun shines bright.

Our bodies are dependent on the sun to function properly. Paleolithic children basked in the sun’s rays, which regulate vitamin D production, brain chemistry, and circadian rhythms (sleep cycles). Today’s kids spend little time outdoors in comparison. Meals and leisure activities often take place inside, with the average 8-18-year-old spending about 7 hours per day in front of a screen (eek!).

Sun is a commodity that is free (tell that to your friends that say the paleo lifestyle is expensive!), ample in summer (I know, this depends on where you live), and provides a wealth of health benefits. This summer is a great time for your family to create a habit of getting as much sun time as possible. A habit to carry out through the school year and beyond.

Vitamin D Production

OutdoorsAbout 90% of the body’s vitamin D is produced by the body when sunlight hits the skin. Vitamin D plays a crucial role throughout the body. It helps metabolize and absorb calcium and other minerals (including zinc, magnesium, iron, and phosphate). It influences proteins that trigger gene expression (that is, turn genes on and off) and has a profound impact on the production of feel-good brain chemicals, such as beta-endorphins and serotonin. It modulates cell growth, neuromuscular function, immune function, and helps reduce inflammation.

Vitamin D is an important compound for kids’ developing bodies. Significant vitamin D deficiency prenatally through the first few months of life can lead to rickets, a disease that is characterized by soft, weak bones and poor motor development. In rats, developmental vitamin D deprivation leads to altered brain structure and function (with altered brain cell growth and “differentiation”) [1], impaired attention and impulsivity. [2] [3]

Scientists have not yet examined vitamin D and cognitive performance in healthy developing children. However, there is undisputed evidence that low vitamin D levels are associated with decreased cognitive functioning in adults and increased risk for dementia and Alzheimers in the elderly. [4] The pattern correlating cognitive deficiencies with low vitamin D likely continues down into childhood (now if only the research would catch up).

Children with ADHD [5], autism [6], and depression have been found to have lower blood levels of vitamin D than their typically developing peers. Researchers don’t yet understand the nature of the relationship between vitamin D and ADHD or autism – are low serum levels of D triggering the expression of genes for these behaviors? Is there a disruption to the biosynthetic process of converting UVB rays into the vitamin D in these children? Time will tell. Intervention studies have not yet been conducted, but it’s possible that exposure to sunlight decreases behaviors associated with those disorders by increasing blood levels of vitamin D serum.

Circadian Rhythm Regulation

Sleeping KidSunlight is necessary to regulate our circadian rhythms (that is, our “internal clock” which determines our sleep/wake cycle). During evolutionary times, being active and awake during nighttime meant an increased chance of being eaten by a mountain lion or falling off a cliff. It was in our best interest to sleep during hours of darkness in order to decrease such risk. Modern amenities have lead to a decreased risk of harm at night, but they have also led to serious disruption of our circadian rhythms.

The American Association of Pediatrics recommends that children sleep about 9-13 hours per night (depending on age). Sleep is a time when hormones and macronutrients go to work in the body so that bones, muscles, and organs can grow. The brain consolidates memories, processes emotions, produces important neurotransmitters in preparation of the day to come, and oxidative stress due to environmental toxins are detoxified.

But a 2004 national survey found that the average kid’s Z’s are falling short.

A 2013 study found that children who increase their daily sleep by one hour had improved emotion regulation, decreased impulsivity, and improved attention and behavior. [7] Restricted sleep has the opposite effect: decreased attention, memory (short and long term), academic performance, as well as difficulty with decision making, behavioral outbursts, depression and anxiety. [8] [9]

Serotonin Production

Exposure to sunlight influences the production of serotonin, a chemical messenger in the brain (neurotransmitter) used to regulate mood and emotion (this is in part due to increased vitamin D and in part due to well balanced circadian rhythms). Researchers believe that serotonin plays an important role in brain development, as children actually have higher levels of serotonin than adults. Increased levels of serotonin is related to feelings of well-being, joy and happiness in children, whereas low levels of serotonin are related to impulsivity, aggression, depression, anxiety and other developmental problems. [10]

More Time Outdoors

photo(1)When kids are outdoors they are less likely to be sedentary. Outside there are infinite ways to get moving, including walking, playing basketball, or climbing at the playground. And if your kids aren’t being active they are still interacting with their environment in ways that are more beneficial to their development than if they are in front of a screen. Playing in the sandbox is great for sensory integration, and playing in the dirt can help improve their immune system. Simply going outside to read or eat a snack can be advantageous. Researchers have found that just hearing sounds and seeing sites of nature can have a positive, calming effect. [11]

Now put down the device on which you are reading this (after you go over and bookmark Happy Paleo Kids, of course 🙂 ) and take your kids to the park (or schedule an evening walk with friends or SOMETHING). Go!


1. Kesby, H.P. et al. (2013). Altered dopamine ontogeny in the developmentally vitamin D deficient rat and its relevance to schizophrenia. Fronteirs in Cellular Neuroscience.
2. Eyles et al. (2009). Developmental vitamin D deficiency causes abnormal brain development. Psychoneuroendocrinology. 34.
3. Turner, et al. (2013). Cognitive performance and response inhibition in developmentally vitamin D deficient rats. Behavioral Brain Research. 242
4. van der Shaft, J., et al. (2013). The association between vitamin D and cognition: A systematic review. Ageing Research Reviews. 12(4).
5. Kamal, M. , Bener, A. & Ehlayel, M.L. (2014) Is high prevalence of vitamin D deficiency a correlate of attention deficit hyperactivity disorder? Attention Deficit Hyperactivity Disorder: 6(2)
6. Duan, X., Jia, F., & Jiang, H. (2013). Relationship between vitamin D and autism spectrum disorder. CPJC: 15(8).
7. Gruber, R., et al. (2012). Impact of sleep extension and restriction on children’s emotional lability and impulsivity. Pediatrics. 130(5).
8. Alhola, A., & Polo-Kantola, P. (2007). Sleep deprivation: Impact on cognitive performance. Neuropsychiatric Disease Treatment. 3(5).
9. Astill, Rebecca G., Kristiaan B. Van Der Heijden, Marinus H. Van IJzendoorn, and Eus JW Van Someren. (2012) Sleep, cognition, and behavioral problems in school-age children: A century of research meta-analyzed. Psychological Bulletin: 138(6).
10. https://www.medicaldaily.com/aggressive-impulsive-behavior-linked-lack-serotonin-receptors-during-brain-development-262541
11. https://www.hopkinsmedicine.org/news/media/releases/natures_sights_and_sounds___but_not_cityscapes_and_noise___ease_spinal_pain_during_bone_marrow_extractions

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36 thoughts on “Why Kids Need the Sun”

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  1. There is a great book called ‘nature shock’ which discusses all of the things modern kids are loosing out on by not spending enough time outside!

    1. Excellent point, and I’m glad to hear you’re taking care of your skin. The research is clear that sunlight benefits our children in many ways. It is important to balance skin safety with sun exposure

  2. Great post for all parents to read 🙂 People are really afraid of the sun now, especially with their kids I think, and need to hear these messages over and over. The summer is a great time for kids to get out and be creative and just play outside.

  3. This is very good information. My youngest daughter actually has Down Syndrome so I will have to pass this on to my wife for her to read as well.

    We’ve also had issues with our girls going to bed easily lately…perhaps the longer days have thrown off their circadian rhythms. Sounds like they need some more time to run around outside! 🙂

  4. I love this post! My kids are 12 and 13 and they are outside running around as I write this 🙂 We have a limitation of screen time – 1 hour a day – and this works really well for us. (We also don’t have, and never had TV – so that was never an issue) My daughter does however have problems falling asleep, and we keep looking for a solution. Although, in her case I think being alone in her room is the main issue :-/ I will for sure book mark your page! Thank you!

    1. Thanks for the feedback, Lisa! It makes such a big difference when we pull our kids away from the screens and have them interact with nature. Best of luck with your daughter’s sleep!

    1. “Circadian Rhythm Section” is a cool band name… Random thought of the day.

  5. Unless I missed it, I didn’t see sunscreen mentioned in the article. I have some friends and family that slather their kids in sunscreen before they ever get out the door. Obviously it’s individual depending on certain factors, but is there a recommendation about how long they should be in the sun (without the sunscreen) for the VitD to kick in? I know they wont abandon it altogether

    1. Bad idea, sunscreen. When I was a kid nobody used sunscreen. You could buy it, but nobody I know bothered. We occasionally got burned, but more often we were just told to cover up or come inside when we started getting pink. I would be far more worried about the toxic chemicals in sunscreen than I would be about my kids getting a bit pink from the sun.

      As to your question, the Vitamin D Council says about 20 minutes between 10am and 2pm should be sufficient to acquire 20,000 iu of natural vitamin D. For fair-skinned people 10 to 15 minutes should suffice.

      1. I could, should, and will write a post on what I call “the great sunscreen debate.”

        When deciding on when to use sunscreen I always weigh 3 factors: 1) benefits of sunlight hitting the skin 2) risk of using sunscreen (phtalates, parabens, aluminum, etc.) and 3) risk of sunburn.

        It is frequent burns that are the biggest sun-related risk factor for skin cancer, not length of time exposed to sun. If you work your kids up to a solid tan then they will burn less easily. Different skin types burn faster than others. Additionally, the sun’s rays are stronger at different times of the year and at different parts of the globe.

        In general, my kids go sans sunscreen unless I know that they will be in direct sunlight for extended periods of time (beach days, amusement parks, long unshaded walks, etc.). In general we alternate between shade and sun when outside to avoid long stretches in direct, strong light.

        Thanks for your question, Sunlover!

  6. Don’t forget that kids who spend more time outdoors (playing outdoor sports, for example) has less incidence of myopia (near-sightedness) than their peers who play inside. Mark did a post on this awhile back.

    Summer swim team is great for a dose of sunlight and who doesn’t like a good water gun fight?

  7. Nice article… basically, everything that is true for adults is true for kids, perhaps plus some!

    I wish that we could get away from the words “screen time” in discussions about kids. I think they play into entirely unnecessary fears about video games or TV “rotting their brains” and the like. Nobody ever talks about limiting their childrens’ reading time, or drawing time, or the time they spend sitting making rainbow-loom creations.

    Notice that the research on adults and activity is generally focused on *being sedentary*, not on making value judgments about what they are doing while being sedentary. I think doing the same thing in discussion about childrens’ health would bring more clarity to the issue.

    1. (Please assume that I really meant to write “children’s” with the apostrophe in the correct spot. Finishing coffee now.)

  8. No! No! No! Everything wrong here. I read on a magazine that children should use a >500 sunscreen from 6am to 8am, avoid sun for the rest of the day and then expose again only from 7pm to 9pm. After that, in order to repair the inevitable damage from that huge supernova our planet is gravitationally bound to, you need to put a dozen of aftersun repair creams. And eat carrots, liver is a filter and is full of toxins!

    1. And then take a vitamin d supplement to make up for not getting it naturally.

    2. Thanks for your comment, Alex. I respectfully disagree. Magazines have a lot of information and it is up to us to decipher their validity. While today’s conventional advice to limit sunscreen has a valid basis – concerns over skin cancer – it is important to balance with our biological need for sunlight exposure, benefits of being outdoors etc.

    3. People have come up with a myriad of reasons to keep children in–the sun, the rain, the snow, pedophiles, child-nappers, drive-by shootings…if the world is so bad that children can’t be CHILDREN, why have them in the first place?

  9. One thought that hit me, while reading this, was “Dear God, can you imagine how bad [my brother’s] behavior would have been if we weren’t getting plenty of sun and sleep?!?!” We lived in the tropics when my older brother was age 9-14. He spent a LOT of time outside, sans sunscreen, and got plenty of sleep. He’s very ADHD, and I shudder to think of how much worse it could have been.

  10. I couldn’t agree more about the importance of kids getting outside and into nature. Kick the kids outside.
    I should note, however, that when it comes to sunscreen you should keep in mind where your ancestors evolved. Those Paleolithic Europeans weren’t hanging out on the beach in Santa Monica.
    If you are a white person living in Scotland or Sweden, get as much sun as you want in the summer (so long as you aren’t burning)! Those few glorious months won’t hurt you. But if your ancestors lived in Scotland (like mine) and you live in the west of the US or Australia, slather up. You’re getting intense UV rays all year round. Both my parents, my grandparents, and almost every white person I know over the age of 55 has had precancerous skin cells removed.
    Having cancer spots removed from your face is both scary and hard on the vanity.
    Even though I am in my 30s, I have a yearly exam, wear sunscreen on my face, and try to avoid prolonged exposure (lounging under a beach umbrella only). My vitamin D levels are fine and I am trying to avoid danger later on.

    1. Loreen,

      Excellent point, and I’m glad to hear you’re taking care of your skin. The research is clear that sunlight benefits our children in many ways. It is important to balance skin safety with sun exposure… and remember, your post-paleolithic Scottish ancestors were receiving some sunlight through those rain clouds and were rarely spending full days indoors. Food still needed to be hunted and gathered. But you are absolutely right that the Scottish body did not evolve to be in direct sunlight all day.

  11. My son is a paper white strawberry redhead. Generally we keep him inside during peak sun and let him out in the morning and evening. If he has to be out during peak sun he is sunscreened and has a hat on(his hair is thin enough to burn through). We are of Swede, Norwegian and German descent living in Western Washington state. Most of the year we have grey and rain except July and August and maybe parts of June and September. It is pretty easy to get crispy when you go from rain straight to full summer sun.

  12. Do you think that doing artwork is as bad as looking at a computer/tv screen? I live in a not-so-safe part of the city that’s not so great for walking around and spend a lot of my free time indoors drawing and painting.

    1. Doing artwork is a great way for children to express creativity, work on fine motor skills, etc. It is enjoyable and is a great developmental activity. But completely excluding outdoor time and exposure to sunlight will likely lead to numerous deficiencies, health-wise and developmentally. Definitely a better choice than screen time, though!

      1. Well, I’m not a child but I’m guessing it’s not too different. I just wonder how different artwork is from screentime. Yes, it’s interactive, but so then are video games. They are both technology, but sketching on wood with a clump of charcoal from the fire is much older than pressing buttons on a computer. I wish I could spend more time outdoors, but it’s not a really welcoming place where I live. When I have kids I hope I’ll live somewhere better.

  13. Very informative, well done! I encourage ALL of my patients to get outside and soak up the sunshine. Start off with less exposure in spring and early summer so not to burn and develop a base tan to be able to tolerate longer sunshine exposure and adequate Vit D as the summer progresses.

  14. I have a job that mixes office and field work, but the field work is not as frequent as I’d like. My serum Vitamin D level was quite low (in the 30’s). I began supplementation, but I also made a habit out of walking outside for at least 15-20 minutes once a day during work hours. In the late morning or early afternoon, when we can get UVA and the ever-important UVB, I walk (out of sight of my office) with my shirt off and no sunscreen (and I live outside of Phoenix, Arizona! I already had some color, but it has been deepening a little bit. The short walking time doesn’t ever cause me to get a burn and I feel fairly refreshed after doing so!

    Love the additional reminders about the role the sub plays and some of the research behind it. Thanks for the article Michelle!

  15. This is all great, but what if I don’t want my kid to get to get too brown

  16. It’s no surprise the mood connection to sunlight too.. I wrote about that in my book how we go stir crazy without adequate Vitamin D. Other studies are also pointing to the fact that low Vitamin D can create chronic low back pain as well.

    We’re meant to live outside!!

  17. Outdoors or Indoors. Hmmm. My gosh. Get outside for a while at the very least!! Sun, rain or snow…whatever. I don’t know of any child that doesn’t like to be outdoors regardless of the weather (to a point, use your head). It’s absolutely criminal that parents / guardians would rather their kids be “safe and sound” indoors versus catching a few rays and scraping a knee or elbow while running around having a blast outside. As for the teens that do nothing but drink coke and watch You Tube videos or play Facebook all day…get outta the house and go do something!! It’s all pretty sad for so many.

  18. Waif a second, despite the massively abundant research showing that sun exposure is negative you are promoting not just a few minutes, but hours? I find this disconcerting considering how popular this website is, I mean there is plenty if questionable health advice but this is just wrong. It’s a fact that uv radiation causes free radical damage, DNA damage to the skin, surpasses the immune system, causes premature aging, increases risk of skin cancer. I think most the views on this site are contrarian just for the sake of it and highly uneducated. You aren’t a scientist, you aren’t a dermatoligist so I’m not sure why so many people follow this horrible advice. Your doctor isn’t out to get you, they’ve studied and worked extremely hard and have far more knowledge than this guy. Listen to your dermatologist and wear sunscreen every day, and limit your sun exposure. Take a supplement if you need vitamin D. The internet is such a double edges sword, it can provide useful information but you have to sort trough the pseudoscience and garbage like this.

  19. It’s good to see people are getting smarter about the human body’s need for the sun. You would be surprised how many serious illnesses and disorders are being linked to a lack of sunlight. I, myself, had Ulcerative Colitis for 20 years and couldn’t figure out why. I finally realized it went away when I got more sunlight. I am so much better now with sun and codliver oil. The intestines cannot process other vitamins without the proper amounts of vitamin D and A. Additionally the brain and the rest of the nervous system will not function properly. There are only two sources of Vitamin D, which is really a hormone, not a vitamin. The sun and animal products, with livers being the best source, and cod livers or other fish livers being the best sources. We have evolved for millions of years on diets that included these and now for a blip of time, we decide this is not right for us? Vitamins you buy in stores, although they say they have it, DO NOT HAVE THE HORMONE WE KNOW AS VITAMIN D.