Nonsmokers who stayed out of the sun had a life expectancy similar to smokers who soaked up the most rays, according to researchers who studied nearly 30,000 Swedish women over 20 years.
This indicates that avoiding the sun "is a risk factor for death of a similar magnitude as smoking," write the authors of the article, published March 21 in the Journal of Internal Medicine. Compared with those with the highest sun exposure, life expectancy for those who avoided sun dropped by 0.6 to 2.1 years.
Pelle Lindqvist, MD, of Karolinska University Hospital in Huddinge, Sweden, and colleagues found that women who seek out the sun were generally at lower risk for cardiovascular disease (CVD) and noncancer/non-CVD diseases such as diabetes, multiple sclerosis, and pulmonary diseases, than those who avoided sun exposure.
And one of the strengths of the study was that results were dose-specific — sunshine benefits went up with amount of exposure.
The researchers acknowledge that longer life expectancy for sunbathers seems paradoxical to the common thinking that sun exposure increases risk for skin cancer.
"We did find an increased risk of...skin cancer. However, the skin cancers that occurred in those exposing themselves to the sun had better prognosis," Dr Lindqvist said.
Given these findings, he told Medscape Medical News, women should not overexpose themselves to sun, but underexposure may be even more dangerous than people think.
"We know in our population, there are three big lifestyle factors [that endanger health]: smoking, being overweight, and inactivity," he said. "Now we know there is a fourth — avoiding sun exposure."
There were 2545 deaths amongst the 29,518 women who responded to the initial questionnaire. We found that all-cause mortality was inversely related to sun exposure habits. The mortality rate amongst avoiders of sun exposure was approximately twofold higher compared with the highest sun exposure group, resulting in excess mortality with a population attributable risk of 3%.