Oh, the sun. This glorious globe of light brings up some complicated feelings in us. Often villainized for its role in skin cancer, but then repeatedly glorified for its contribution to our production of vitamin D. Ultraviolet radiation (UVR) from the sun is unique in that it is one of the few environmental exposures that both causes and protects from disease. So, where does this leave us? Where does the scale tip? Should we get sun, or avoid it at all costs?
Risks of sun exposure & risks of sun avoidance
Let’s start with some myth-busting. When it comes to the sun, just like with anything else, there can be too much of a good thing. It’s indisputable that excessive UVR from the sun can contribute to several health risks, including skin cancer, aging of the skin, and cataracts. But this doesn’t mean we need to fear the sun. In a report by the World Health Organization that reviewed the total burden of disease related to excessive UVR, the contribution was found to be minimal (0.1% of the total global disease burden). Many of the diseases that can be directly linked to excessive UVR are relatively benign, except for malignant melanoma, which has an incidence of 21.8 cases per 100,000 people. However, this same report found that the disease burden of getting too little UVR is twice as high– 1.6 million disability-adjusted life years (DALYs) from too much UVR vs. 3.6 million DALYs from not enough UVR. Too little sun exposure can have numerous deleterious effects, including cancer, immune system dysfunction, and vitamin D deficiency which can contribute to rickets and osteoporosis.
Why you should still get regular sun exposure
Vitamin D. Of course, the best-known health benefit of sun exposure is vitamin D production. Vitamin D affects at least 1,000 different genes that govern essentially every tissue in the body! It is deeply involved in calcium metabolism, musculoskeletal health, and immune system function. The importance of achieving optimal vitamin D levels in the pursuit of health cannot be overstated. Although there are very few food sources of vitamin D, we can produce our own via sufficient exposure of our skin to the sun.
Circadian Rhythm. When we view bright light first thing in the morning (preferably within the first hour), this has a powerful impact on wakefulness, sleeping, and hormones. Optic exposure to daylight stops melatonin production, leading to increased wakefulness in the morning and earlier production in the evening, which helps us fall asleep more easily at night. Bright morning light exposure and its effects on melatonin have been effective against insomnia, PMS, and seasonal affective disorder (SAD).
Reconnect with nature. I once heard vitamin D deficiency explained as a symptom of our disconnection with nature. Getting outside every day for your dose of sunshine has innumerable other benefits on our mental and physical health.
Balance hormones and improve libido. Regular sun exposure, especially optic exposure to morning light, can help balance our hormones, including estrogen and testosterone, leading to improved libido. This is part of the reason why we see animals begin to breed in spring and summer when days are longer and they are getting more sunlight.
Mood elevation. We have all experienced the joy that comes from feeling the warm sun on our skin; many are also familiar with experiencing the “winter blues” or decreased mood after a long stretch of rainy days. Sunlight is a powerful mood modulator, partially thanks to the serotonin and dopamine boost with exposure.
Improve immunity. According to, William Grant, who directs the Sunlight, Nutrition, and Health Research Center in California, “Vitamin D induces cathelicidin, a polypeptide that effectively combats both bacterial and viral infections… this mechanism explains much of the seasonality of such viral infections as influenza, bronchitis, and gastroenteritis, and bacterial infections such as tuberculosis and septicemia”. Low vitamin D levels are also thought to be linked to many autoimmune diseases.
Prevent chronic disease. Multiple studies have shown the benefits of regular sun exposure in the prevention of multiple sclerosis, diabetes, hypertension and cardiovascular disease, cancer, and various other diseases.
Where should you start?
Prioritize getting at least a few minutes of sunlight within 1 hour of waking. Bonus points if you achieve this through a morning walk which will yield additional benefits (especially helpful if you suffer from SAD). Keep in mind that sunlight filtered through the window may not have the same effects so try getting outside, even if just for 5 minutes while you enjoy your coffee. Since optic exposure to light is essential for neurotransmitter release, make sure to go shades-free during daylight hours, even for just 10-15 minutes per day.
There is not necessarily a one-size-fits-all approach to what constitutes healthy levels of UVR exposure vs. excessive. This depends on where you live, what time of day you are getting outside, how much skin is exposed, the color of your skin, and many other factors. For example, a white person who sunbathes in a bathing suit for 30 minutes in the summer can produce 50,000 IU of vitamin D, while a dark-skinned person may only release 8,000 IU of vitamin D in this period thanks to the protective effects of melanin. Start slow and listen to your body. Aim for brief, repeated exposures to the sun vs. one long exposure which will help to avoid sunburn and some of the other risks of sun exposure. Getting 12-15 minutes of midday sun is generally a good place to start for most individuals. You can also use an intuitive app, like DMinder, which can help you to estimate how much vitamin D you are producing based on your location and the UV index for that day.
If you’re unable to get regular sun exposure or know you suffer from vitamin D deficiency, consider a vitamin D supplement. Most people can benefit from 2000-6000 IU of vitamin D3 daily, based on their level of sun exposure and baseline vitamin D levels. (Pro tip: since vitamin D is a fat-soluble vitamin, it should always be taken with a fat-containing meal to improve absorption). But keep in mind that sun exposure confers many benefits outside of vitamin D production (as discussed above), so going straight to the source is still ideal.
TLDR; While there are risks associated with too much ultraviolet radiation from the sun, there is also significant health risks associated with too little sun exposure
Regular sun exposure has innumerable health benefits, including vitamin D production, circadian rhythm alignment, reconnecting with nature, hormone optimization, mood elevation, improved immunity, and others
Try to get sunlight as close to waking up as possible & go shades free during the day
Aim for brief, repeated exposures to the sun throughout the day & listen to your body
If you can’t get regular sun exposure or have a vitamin D deficiency, consider supplementing with 2000-6000 IU of vitamin D3 daily, taken with a fat-containing meal
References
Centers for Disease Control and Prevention. “Melanoma Incidence and Mortality, United States – 2012-2016.” USCS Data Brief, no. 9. Atlanta, GA: Centers for Disease Control and Prevention, US Department of Health and Human Services; 2019, acsjournals.onlinelibrary.wiley.com/doi/full/10.3322/caac.21551
Juzeniene, Asta, et al. “Solar Radiation and Human Health.” Reports on Progress in Physics, 74,6 (2011): 066701.
Lucas, Robyn M et al. “Estimating the Global Disease Burden due to Ultraviolet Radiation Exposure.” International Journal of Epidemiology vol. 37,3 (2008): 654-67. doi:10.1093/ije/dyn017
Mead, M Nathaniel. “Benefits of Sunlight: A Bright Spot for Human Health.” Environmental Health Perspectives vol. 116,4 (2008): A160-7. doi:10.1289/ehp.116-a160
