The number was even higher for those exposed to sunlight as children. Women who spent lots of time in the sun between ages 5 and 15 were 51 percent less likely to get multiple sclerosis, compared to those who lived in shadier areas during the same time span.
"Our findings suggest that a higher exposure to the sun's UV-B rays, higher summer outdoor exposure and lower risk of MS can occur not just in childhood, but into early adulthood as well," co-author Helen Tremlett said in a statement.
Why is that?
UV-B rays help the body produce vitamin D, and lower levels of vitamin D have been associated with an increased risk of multiple sclerosis. Scientists believe the more vitamin D a person has the more likely they are to dodge a diagnosis.
While they did note that the sun exposure numbers were self-reported and the individuals’ measurements may differ from actual exposure time, they believe their results are promising.
"While previous studies have shown that more sun exposure may contribute to a lower risk of MS, our study went further, looking at exposure over a person's life span. We found that where a person lives and the ages at which they are exposed to the sun's UV-B rays may play important roles in reducing the risk of MS," Tremlett said. "The methods we applied to measure sun exposure could also be used in future studies."