Sunshine offers more than just sunburns; in fact, it may just be the best medicine you never pay for. The sun gets a bad rap these days—with many Americans thinking that it offers little but skin cancer—but soaking up those golden rays can do more good than harm.
During the past half-century, research and the public have focused on the sun’s health risks, especially skin cancer, overshadowing the numerous studies that link sunlight to positive physical and mental health.
Of course, severe burns can still cause melanoma. That’s why moderation is key to reaping sunlight’s healthy rewards without the painful burns.
Avoiding Sun Exposure Has Become a ‘Public Health Problem’
A 2020 scientific review published in the International Journal of Environmental Research and Public Health detailed findings from a collection of studies that showed that avoiding sunlight can be hazardous and suggested that insufficient sun exposure may have led to as many as 820,000 deaths yearly in the United States and Europe.
“Studies in the past decade indicate that insufficient sun exposure may be responsible for 340,000 deaths in the United States and 480,000 deaths in Europe per year, and an increased incidence of breast cancer, colorectal cancer, hypertension, cardiovascular disease, metabolic syndrome, multiple sclerosis, Alzheimer’s disease, autism, asthma, Type 1 diabetes, and myopia,” the researchers reported.
“Insufficient sun exposure is a significant public health problem.”
The comprehensive review noted that vitamin D supplementation didn’t have the same preventative effect on these conditions, likely because other mechanisms triggered by sunlight—such as the release of nitric oxide from the skin and the direct effects of ultraviolet radiation on peripheral blood cells—may be the active factors in reducing these conditions.
Sun’s Rays May Prevent Heart Disease
Cardiovascular disease is the leading cause of mortality worldwide, killing almost 18 million people annually.
Evidence suggests a strong correlation between sun exposure and positive impacts on hypertension, a significant risk factor for heart disease and cerebral vascular diseases affecting blood flow to the brain.
Recent research indicates that sunlight lowers blood pressure by mobilizing nitric oxide stored in the skin, thereby enhancing nitric oxide availability, which dilates blood vessels. By promoting vasodilation, nitric oxide helps regulate blood flow to different tissues and organs in the body.
In addition to improving blood flow and lowering blood pressure—both of which reduce stroke risk—sunlight exposure increases vitamin D levels, which are also associated with a lower risk of stroke.
Vitamin D from sunlight may help inhibit inflammation in blood vessels and help prevent clot formation, potentially reducing stroke risk.
Avoiding the Sun May Be as Harmful as Smoking: Study
Modern lifestyles, characterized by indoor jobs, fewer outdoor activities, and the widespread use of air conditioning, have led to reduced sun exposure for many individuals. Additionally, people stay indoors for activities that used to compel a trip outside, such as buying food and clothes. These changes raise concerns about their potential impact on life expectancy.
A study that observed about 40,000 Swedish women aged 25 to 64 revealed that sun avoidance was as risky as smoking. Published in the Journal of Internal Medicine in 2016, the study integrated data from a study that included about 1,000 women from each age group for 20 years.
Women who regularly exposed themselves to the sun had a lower risk of cardiovascular disease and other diseases, except for cancer, than those who avoided sunlight. The sun-exposed group had an average life expectancy that was six months to two years longer. The increased cancer mortality rate among sun-exposed women was attributed to the women living longer, as age is a significant risk factor for developing cancer.
Sunlight May Prevent Chronic Conditions
Type 1 Diabetes
Sun exposure during pregnancy may prevent Type 1, or juvenile, diabetes, according to a 2016 Danish study that included more than 330,000 children, more than half of them male. After 15 years of observation, researchers found that boys aged 5 to 9 whose mothers received more sunlight exposure during their third trimester had a reduced risk of developing Type 1 diabetes. The protective effect, however, wasn’t observed in girls.
An Australian study of about 29,000 boys published in Nature in 2021 also showed that those exposed to a higher rate of UV (ultraviolet) rays during their first year of life or third trimester of gestation were at a lower risk of Type 1 diabetes.
Multiple Sclerosis
Multiple studies have shown that sun exposure correlates with reduced risk for multiple sclerosis (MS). MS damages nerve fibers, causing symptoms such as paralysis and blindness.
An Australian study found that those who spent an average of at least two hours in the sun daily as children had a lower MS risk than those who had fewer than two hours of sun exposure daily.
A study of 1,660 MS patients and 3,050 control subjects in Norway and Italy also found that infrequent summer sun exposure significantly increased MS risk, especially for Norwegians aged 16 to 18 and Italians up to 5 years old.
A 2012 Swedish study (pdf) concluded that independent of vitamin D, sunlight might protect against developing MS. The five-year study of more than 2,000 subjects found that those with the least sun exposure had higher MS risk regardless of vitamin D levels. Sunlight’s physiological mechanisms, beyond boosting vitamin D, may help explain its link to lower MS risk.
Eczema and Allergies
Eczema commonly manifests in infancy or early childhood. In a 2018 study, researchers discovered that infants exposed to more direct UV light had lower rates of eczema and inflammation indicators.
It also found that direct UV light exposure in the first months of life was more effective for allergy prevention than vitamin D supplementation alone.
Melanoma
While intermittent sun exposure increases the risk of melanoma—the most severe and invasive form of skin cancer—ongoing sun exposure may have a protective effect.
Research from the University of Sydney in Australia found that workers with continuous sun exposure from their jobs weren’t at higher melanoma risk than the general population. Moreover, their risk wasn’t compromised by recreational sun exposure on weekends.
How Much Sun Exposure Is Too Much?
In light of recent research showing how sunlight improves health, there has been a call for new sun exposure guidelines.
A 2021 research article recommends that scientists—including dermatologists and epidemiologists—review public health guidelines that balance the risks and benefits of sun exposure, particularly for optimal vitamin D levels.
Current guidelines from dermatology groups tend to emphasize sun protection to reduce skin cancer risk while overlooking the benefits.
