Spend too much time in the sun, and you may get a sunburn and possibly skin cancer. Spend too little, and you may get depressed and come down with rickets.
Sunscreen used to be the solution, but now we know that some brands contain potentially harmful toxins. Then there's the upcoming eclipse, which will be visible over much of the continental U.S. on Aug. 21. The eclipse is probably not a harbinger of doom for the planet, like some people say, but you'll want to take some precautions that day, according to NASA.
With summer approaching, sorting through the pros and cons of sunlight could force someone into hiding. But that wouldn't be the most healthy choice for you or your family, either.
The latest research can give some guidance on how to reap the rewards and reduce the risks that come with sunny weather.
The benefits of sun
Unless you’re a vampire, small amounts of sun are good for you and benefit both physical and mental health. That’s not just what controversial osteopathic doctor Joseph Mercola says, but the World Health Organization.
Mercola, who has been dubbed both visionary and quack, was sued by the Federal Trade Commission for false advertising after he sold tanning beds, telling customers that using them would cut their cancer risk. Last year, Mercola agreed to refund up to $5 million as part of a settlement, the Chicago Tribune reported, but he continues to preach on his popular website that “sensible sun exposure does more good than harm.”
This may surprise people who have been hiding under beach umbrellas and hats for the past few years, but the World Health Organization says as much.
“Small amounts of UV are beneficial for people and essential in the production of vitamin D. UV radiation is also used to treat several diseases, including rickets, psoriasis, eczema and jaundice,” the agency says on its website.
Vitamin D, which the body makes after sun exposure, is necessary for calcium absorption and bone health, which has lead some researchers to believe that the increase in osteoporosis is due in part to people spending less time outside.
A bone disease called rickets was common among American children before the 20th century, but it diminished after doctors found that vitamin D deficiency was the cause, leading to widespread fortification of milk with vitamin D.
Besides being good for our bones and treating some skin conditions, moderate sun exposure is associated with better mood and cognition, and even seeing the sun through office windows, particularly early in the morning, appears to improve sleep and energy.
Simply being attuned to the sun and its cycles can improve a person's sleep, which affects our overall health. Research from the University of Colorado, Boulder, has shown that outdoor camping can help people with insomnia by resetting their body's inner clocks.
And a Swedish study published in 2014 found that women who had little to no sun exposure were more likely to die than women who regularly sunbathed.
The line between benefit and risk
With all the benefits of the sun, it's not surprising that some people overdo their exposure, with harmful results.
The quickest, and most visible, is a painful sunburn, which not only makes you miserable but raises your risk for skin cancer and, when it happens to a child, can even get a parent arrested for child neglect or abuse, as was the case with a couple in Florida.
A sunburn occurs when the body’s natural healing ability is overwhelmed by the amount of damage to the skin. The redness is caused by the dilation of blood vessels, and peeling is a sign that your DNA has been damaged.
“Your body can deal with some of the damage from a sunburn, but if you get too much DNA damage, the repair system can’t keep up so your body has to start shedding. The peeling of the skin is the body’s way of getting rid of that damaged DNA,” Megan Thielking of STAT reported.
Children are particularly vulnerable to sunburn, and just one serious sunburn in childhood can double the risk of melanoma later in life. Sun exposure is associated with 86 percent of melanomas, a dangerous form of skin cancer, The Miami Herald reported.
The Centers for Disease Control and Prevention takes a hard-line stance on sun, saying Americans should strive to get vitamin D from food, not the sun.
"The skin can produce only a limited amount of vitamin D at one time. Once the body has reached this limit, spending more time in the sun will not continue to increase vitamin D levels. However, continued time in the sun will increase your skin cancer risk," the CDC says.
How much vitamin D your body produces after sun exposure depends on your complexion, where you live, what time you're outside and what you're wearing.
But generally, a fair-skinned person who goes outside midday in a tank top and shorts will obtain about 10,000 international units, according to U.S. News and World Report.
The government recommends that American adults have from 400 to 800 international units a day, depending on age. (Senior adults need the higher levels.)
The skinny on sunscreen
For years, sunscreen was thought to be an easy way to enjoy the sun without its risks. But concerns about chemicals have made some parents wary of putting the lotion on their children.
For 11 years, the Environmental Working Group has released a guide to sunscreens at the beginning of summer. In this year's report, the group said three-quarters of the sunscreens it tested either worked poorly or contained chemicals such as oxybenzone, which some people believe interferes with our hormones. (The chemical is now blamed for destroying coral reefs, and for that reason, Hawaii could be the first state to ban sunscreens containing oxybenzone.)
The report was quickly challenged by another advocacy group, The Center for Accountability in Science, which accused the Environmental Working Group of promoting "chemical hysteria" and pointed to a 2011 study that said there's no evidence that repeated absorption of oxybenzone is toxic. You'd have to apply it daily for 200 years before it reached dangerous levels, the center said.
Consumer Reports, however, concurs with the Environmental Working Group's assertion that sunscreens don't always deliver the benefits advertised, regardless of ingredients.
"Of the more than 60 lotions, sprays, sticks, and lip balms in our ratings this year, 23 tested at less than half their labeled SPF number," Trisha Calvo of Consumer Reports said, noting that manufacturers test their own products and the FDA does not evaluate their claims.
The American Cancer Society doesn't weigh in on which sunscreens to buy or avoid, but it does offer three tips: Look for products that say they offer "broad-spectrum protection" (meaning they protect against both UVA and UVB rays); buy a product with an SPF (sun protection factor) of at least 30; and know that there's no such thing as a "waterproof" sunscreen, only water-resistant.
Dr. Debjani Sahni, a dermatologist with Boston Medical Center, told STAT that an SPF beyond 50 does not offer much more benefit.
Infants 6 months and younger shouldn't have sunscreen on them at all, the Food and Drug Administration says — in fact, the FDA says to keep babies that young out of the sun completely.
About that eclipse
With or without sunscreen, Americans should use extra caution on Aug. 21, the day of the first total eclipse in North America in 38 years.
How dangerous the sun is on that day depends on where you are, and what time it is — but it's your family's eyes, not their skin, that's at risk.
According to NASA, 14 states — stretching from Oregon to South Carolina — are in the "path of totality" where the total eclipse will be visible. The moment of total eclipse (when the moon completely blocks the sun) is not dangerous, but it's the partial eclipse that leads up to it that can damage your eyes. And most Americans will only see a partial eclipse.
NASA says that the only way to safely view a partial eclipse is with special glasses or solar viewers. "Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun," the NASA website says.
To date, the space agency endorses only the eclipse glasses and solar viewers produced by these companies: Rainbow Symphony, American Paper Optics, Thousand Oaks Optical, and TSE 17.
Looking at a partial eclipse without protection can cause retinal burns and vision loss, and the most vulnerable people are children and young adults, NASA says.