Spending This Much Time Outside Each Day Could Make You Live Longer
A breath of fresh air can do the body and the spirit good. Recent research says much of it comes down to how much sunlight you need every day.
Today’s indoor lifestyles are keeping us from living our lives to the fullest—literally. One 2020 study published in the International Journal of Environmental Research and Public Health (IJERPH) found that insufficient day-to-day sun exposure could be responsible for 340,000 premature deaths in the US each year—and not getting enough sunlight may play a role in increased rates of cancer, heart disease, diabetes, and cognitive disorders.
In fact, “research has identified a positive link amongst centenarians—those who’ve reached 100 years [of age]—and outdoor time,” explains naturopathic doctor Natasha Vani, ND, MSc at Newtopia. One 2022 study even found that most centenarians share the same hobby: Getting daily sunshine by gardening. Another study monitored 30,000 women for 20 years, finding that those with active sun exposure habits saw a much lower risk of cancer and heart disease—and that sun avoidance is a risk factor for premature death of a similar magnitude as smoking.
Still, dermatologists warn us of the dangers of too much sun exposure…so how much sunlight do you need a day?
How does sunlight help you live longer?
The IJERPH research points to the biggest benefit sun exposure brings to our health: Vitamin D. Multiple trend reports show a huge increase in vitamin D deficiencies over the past few decades—today, an estimated 24.6% of people are deficient, while another 41% of us have insufficient levels.
Experts have long addressed these low levels as a “silent epidemic” because symptoms can be subtle. Health consequences may not emerge for years or decades, as low vitamin D levels are associated with a greater risk of developing a wide range of chronic illnesses. Yet the COVID-19 pandemic brought the issue into the spotlight, with research showing people with vitamin D deficiency were nearly twice as likely to test positive for COVID-19.
“We can take vitamin D supplements and consume vitamin D-rich foods, [but] regular exposure to sunlight is by far the most practical, cost-effective, and efficient way to optimize levels,” Dr. Vani says. In fact, research suggests vitamin D food intake on a standard diet makes up only about 10% of National Institute of Health’s recommended daily amount (600 IU for children and adults and 800 IU for those over age 70)—and some diets make it even harder to eat enough vitamin D.
How much sunlight do you need a day?
While regular sun exposure is an efficient way to get sufficient vitamin D, the optimal amount of time you spend soaking up the sun depends on a lot of variables, says Dr. Jennifer Bahrman, PhD, a psychologist with UTHealth Houston. Location, time of year, and time of day are major factors that dictate the strength of the sun’s rays hitting your skin. (Cloud-cover isn’t one of them, though—sun rays still pass through clouds so you can get your share of vitamin D.)
Researchers in Valencia, Spain (at a similar latitude to areas of the US like South New Jersey, Denver, Colorado, and Sacramento, California) found that in summer months, 10 minutes of sun exposure mid-day and 20 minutes of sun exposure in the evening produced sufficient vitamin D levels in the skin.
However, in the winter, you’d need about two hours in the sun mid-day—and much longer in the morning or evening. A study from Switzerland (comparable in latitude to US states along the Canadian border) found similar results: In summer and spring, spending 10 to 15 minutes in the sun gets you enough vitamin D for the day—but it’s tough to reach those levels in winter.
Your skin tone and age matter in how much sunlight you need a day, too. Those with darker skin tones don’t make as much vitamin D because their skin’s pigmentation reduces its production. It’s also believed that as our skin ages, its ability to produce vitamin D declines.
So there isn’t a hard-and-fast rule for how much sunlight you should get, but in general, “it’s recommended people get between five and 15 minutes of sunlight, several times a week,” Dr. Bahrman says. And people with darker skin tones may need up to 30 minutes for optimal benefits. “Talk to your doctor to discuss what’s right for you,” she advises.
How do I get enough vitamin D in the winter?
As the research shows, if you live in a wintry climate it can be difficult to get enough vitamin D from sunlight alone—and that’s where prioritizing vitamin D-rich foods and taking a high-quality supplement can help fill the gap. (Here are the 4 best vitamin D supplements, according to nutritionists.) But experts say it’s still important to get those 15 minutes in the sun. First of all, spending time outside reduces stress by lowering cortisol (our stress hormone,) enhances working memory, improves mood, and decreases anxiety levels, Dr. Bahrman says.
Sunlight also helps the body release serotonin, a hormone most well-known for its effect on regulating our mood and emotional well-being. But it also plays a big role in our sleep and eating habits—which is why sun exposure is one of the best ways to manage seasonal affective disorder (SAD.) Getting a daily dose of sunlight during those dark winter months is important for keeping your circadian rhythm in check, too, so you sleep better at night.
But no matter the time of year, don’t skip sunscreen. While SPF does block the sun’s skin cancer-causing UV rays, a review of research published in the British Journal of Dermatology says that there’s little evidence sunscreen decreases vitamin D production in your skin.
Natasha Vani, ND, MSc, VP Program Development and Operations at Newtopia
Dr. Jennifer Bahrman, psychologist, assistant professor of psychiatry and behavioral sciences with McGovern Medical School at UTHealth Houston
National Institutes of Health: "Vitamin D"
International Journal of Environmental Research and Public Health: "Insufficient Sun Exposure Has Become a Real Public Health Problem"
Vienna Yearbook of Population Research: "The Blue Zones: areas of exceptional longevity around the world"
Journal of Population Aging: "Blue Zones: Centenarian Modes of Physical Activity: A Scoping Review"
Journal of Internal Medicine: "Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort"
Pediatrics: "Trends in the Diagnosis of Vitamin D Deficiency"
JAMA: "Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results"
Journal of Exposure Science & Environmental Epidemiology: "Estimation of exposure durations for vitamin D production and sunburn risk in Switzerland"
Science of The Total Environment: "Solar ultraviolet doses and vitamin D in a northern mid-latitude"
The Journal of Nutrition: "Vitamin D and African Americans"
Nature: "A Comparison Study of Vitamin D Deficiency among Older Adults in China and the United States"
British Journal of Dermatology: "The effect of sunscreen on vitamin D: a review"