A little bit of sunlight can do a lot of good for your health.
There’s a constellation of freckles and moles on my body that inspires dread before every dermatologist appointment. Without fail, my biannual skin-cancer screenings result in a biopsy or two — along with a renewed commitment to regularly slathering myself in SPF 50.
Even with those precautions, I steer clear of the sun like a vampire. I take epic measures to avoid midday exposure: long sleeves in 90-degree weather, wide-brimmed hats, swapping seats with friends when dining alfresco to hog as much shade as possible — the list goes on.
Until recently, I assumed there was no downside to hiding from the sun. For the last three decades or so, as the incidence of skin cancer has risen dramatically (it’s now the most common form of cancer worldwide), health experts have focused their attention primarily on the hazards of excessive sun exposure.
In 2014, even the U.S. surgeon general issued a warning about the dangers of the sun.
And yet, according to renowned vitamin D researcher and integrative physician Gregory Plotnikoff, MD, the surgeon general has also issued reports identifying osteoporosis as a public health crisis.
This bone-weakening condition is related directly to a lack of vitamin D, something the body manufactures only when it is exposed to the sun. Plotnikoff also notes that a wealth of observational data has implicated vitamin D deficiency in 17 kinds of cancer, including skin cancer.
How’s that for a conundrum?
One study published in JAMA Internal Medicine in 2009 found that nearly 70 percent of Caucasians, 90 percent of Mexican Americans, and 97 percent of African Americans in the United States have insufficient blood levels of vitamin D. This deficiency is now thought to be one of the most common medical conditions in the world, affecting an estimated 1 billion people. And it’s prompting many health professionals to pipe up about the detriments of excessive sun avoidance — and the importance of a little sunlight.
“Sun exposure is the single most cost-effective medical intervention we have,” says Plotnikoff, citing the sun’s free boost of vitamin D.
Nonetheless, Plotnikoff and others emphasize that there are healthy and unhealthy ways to soak up the rays. Sunburns and dark tans are still a health risk. Moderation is key. But moderation is also harder to teach, so many professionals default to the simpler directive.
“The easier message is to say ‘no unprotected sun exposure at all,’” says Valori Treloar, MD, an integrative dermatologist in Newton, Mass. “But while the middle road may be a more complicated message to convey, I believe it’s the right one.”
Here are the facts on why we all need some time in the sun — and how we can get it safely.
The Sun-Health Connection
Sufficient sun exposure is essential to optimal health for three key reasons:
1. Sun triggers vitamin D synthesis. Sunlight doesn’t technically supply us with vitamin D; our bodies produce their own when UVB rays contact the skin. Although it’s classified as a vitamin, vitamin D behaves more like a hormone, affecting the expression of our genes and interacting with almost every cell in the body directly or indirectly.
“It’s important for people to know that vitamin D is not just important for bone health,” Plotnikoff explains. “It affects muscular function, immune function, and brain function. There are receptors for it in almost every organ in the body.”
There’s evidence that adequate vitamin D levels can reduce cancer risk by as much as 30 percent, according to Edward Giovannucci, MD, ScD, a professor of nutrition and epidemiology at Harvard University’s School of Public Health.
In one study at the University of California, San Diego, researchers found a link between low vitamin D levels and a higher risk of colorectal and breast cancers.
Perhaps even more notably, a 2009 study at the University of Leeds in England found that higher levels of vitamin D were linked to improved skin-cancer survival rates.
Vitamin D also affects cardiac health. Research published in JAMA Internal Medicine shows that those with the lowest vitamin D levels have a 20 percent greater risk of dying from heart disease over an eight-year period compared with those with the highest levels.
Finally, vitamin D may even help prevent athletic injuries. Plotnikoff points to a study that found that NFL players with low levels of D were at higher risk of injury and preseason release than players whose levels were optimal.
2. Sunlight supports healthy sleep patterns. “Getting sunlight in the morning helps regulate your circadian rhythms and makes you alert at the start of your day,” says Cathy Wong, ND, a naturopathic physician in Boston.
When the sun’s rays hit your eyes, she explains, the optic nerve sends a message to the pineal gland at the center of the brain to stop producing melatonin, a hormone that helps you sleep. When the sun goes down, your production of sleep-inducing melatonin increases again. (For more on the health-related science of circadian rhythms, see “Light Rhythms“.)
3. Sun supports brighter moods.
A 2014 study published in the journal Cell found that exposure to ultraviolet radiation causes the release of endorphins — those feel-good chemicals that not only boost spirits but also relieve pain.
A 2008 study reported in Proceedings of the National Academy of Sciences of the United States of America showed that rats deprived of light for six weeks not only exhibited signs of depression, they also experienced damage in the regions of the brain associated with human depression.
Right Size Your Intake
Experts agree that a little sun can go a long way. A typical recommendation is to get between five and 20 minutes of midday sun depending on skin type, season, and other variables, but Plotnikoff disagrees with the recommendation and emphasizes that there is no “one size fits all” prescription.
The critical factor is to avoid burning (even a little) at all costs. “If your skin is white and starts to pink up,” he advises, “take cover.” Plotnikoff notes that while darker skin generally has more built-in protection, it can still burn, so it’s important to be cautious.
Here are more tips for getting the sunshine you need — without exposing yourself to unnecessary risks.
- Know your skin type. The fairer you are, the less unprotected sun exposure you’ll need to produce adequate vitamin D, since lighter skin synthesizes it more quickly. Darker skin requires more exposure for adequate vitamin D production.
“In general, a range of about five minutes for those with very fair skin to about 20 minutes for those with darker complexions is adequate,” says Holly Lucille, ND, RN, a naturopathic doctor in Los Angeles.
There are a few caveats, notes Treloar: “If you’ve had multiple skin cancers, a history of malignant melanoma, or a genetic disease that prohibits sun exposure, the benefits of steering clear of the sun far outweigh those of getting even a little unprotected exposure,” she says. “If you fall in one of these categories, vitamin D supplements become crucial.”
- Expose strategically. For both your health and beauty’s sake, you might want to expose skin that’s less vulnerable to dark spots and wrinkles. While it’s often easiest to get some midday sun on your face, chest, and arms, those are also the very areas that tend to get overexposed, says Treloar. “If your face, chest, and arms are already showing the signs of sun damage, those are areas you should always keep protected.”
Wong adds that “the more of you that’s exposed, the less time in the sun you’ll need to make vitamin D.” So, consider covering up your face and exposing just your legs, for example.
- Aim for midday sun. We’ve all been taught to avoid the sun at midday, but this is when UVB rays (which are required to synthesize vitamin D) are at their strongest. In other words, this is when you can make maximum vitamin D with minimum sun exposure.
- Check the UV index in your area to see if UVB rays are strong enough to trigger vitamin D synthesis.
The United States Environmental Protection Agency offers a free UV Index forecast that can clue you in to the UV Index in your area (available via the EPA’s SunWise UV Index app or at EPA UV Index). If it’s less than 3, it’s likely you’re not getting enough UVB rays to produce vitamin D — even from midday sun.
In northern regions where the sun sits low in the sky during winter months, “you could be stark naked at high noon in the middle of the town square and still not make enough vitamin D,” Plotnikoff says.
He recommends this rule of thumb: “If you’re outside and your shadow is shorter than you are tall, you can make vitamin D.”
- Fill your vitamin D gaps. Depending on your geographic location and lifestyle, you might not be able to meet your vitamin D needs by relying exclusively on sun exposure, even if you are outdoors a fair bit.
“Last summer, I played tennis regularly outdoors and was getting the recommended 10 to 15 minutes of unprotected sun exposure on my medium-toned skin,” says Wong. “And my vitamin D levels were still low when I was tested in October.”
We all synthesize vitamin D differently, Plotnikoff notes, so many people will need higher doses to keep levels optimal. For example, athletes and slender women who are at risk for osteoporosis because of their low body mass generally need more vitamin D. Even our genes can affect how rapidly we metabolize vitamin D; in fast metabolizers, levels drop more quickly.
The bottom line: For optimal levels of vitamin D, most of us will need to supplement. While the recommended daily allowance for adults is 600 IUs, Wong says many experts recommend 1,000 IUs or higher, so talk to your practitioner about getting your levels checked and finding the dosage that’s right for you.