Here Comes the Sun

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Years of dismal warnings about the dangers of sun exposure have taught many people who naturally crave sunlight to avoid it. Now there is evidence that, in older people, too little sunshine can increase susceptibility to a range of serious diseases. Sunlight has its bright side after all.

One of sunshine's most pleasant and obvious effects is its ability to cheer people up and make them more alert. As light from the sun's rays travels via the optic nerve to the brain, it stimulates production of serotonin, one of the body's "feel good" chemicals. The flip side of that effect is how the coming of winter, when the days grow shorter and give us less exposure to sunlight, can cause depression.

An intriguing new finding related to sunlight's effect on mood suggests it might ease post-surgical pain. Bruce Rabin, medical director of the lifestyle program at the University of Pittsburgh Medical Center, found that patients who were placed in sunlit rooms after surgery reported less pain and took less pain medication than those in darker rooms. "We believe it's serotonin elevation that accounts for it," he says. Rabin suspects that sunlight can also dampen pain perception from other conditions, such as arthritis.

But it is direct sunlight taken through the skin, well known in the body's production of vitamin D, that has proved to be more important to good health than scientists previously suspected. Studies now show that vitamin D not only helps the body absorb calcium, building stronger bones, but also protects against a host of other problems, including heart disease, rheumatoid arthritis, multiple sclerosis and cancers of the breast, prostate and colon. Vitamin D deficiency has also been linked to an increased risk of falls among people over 65 and to persistent and unexplained bone and joint pain.

A recent study concluded that sunlight reduced the risk of developing a cancer of the lymphatic system that most often affects people over 50. When he began to study the relationship of sun exposure to non-Hodgkin's lymphoma, Bruce Armstrong, head of the University of Sydney School of Public Health, expected to find that the more time people spent in the sun, the more likely they were to develop the disease. To his surprise, men and women who got the most sunlight (other than those who worked all day in the sun) had the lowest risk.

Only 20 minutes of sunscreen-free exposure several times a week makes plenty of vitamin D, yet many older people aren't getting enough of it. "Probably 40 percent of otherwise healthy adults between 49 and 65 years old and half of all people over 65 are deficient," says Michael Holick, who runs the Vitamin D, Skin and Bone Research Laboratory at Boston University Medical Center.

The American Academy of Dermatology states unequivocally that unprotected sun exposure is never safe because of the risk of skin cancer. Experts do believe that excessive sun exposure and sunburn cause skin cancer. But according to Francis Gasparro, adjunct research professor of dermatology at Thomas Jefferson University in Philadelphia, "there's not a whole lot of direct evidence that sunscreens prevent skin cancer and virtually none that they prevent melanoma, the deadliest form."

Marianne Berwick, head of epidemiology and cancer prevention at the University of New Mexico, thinks the low levels of exposure needed to make vitamin D won't hurt anyone. "That amount won't increase your chances of developing cancer," she says. "If you're going to remain outdoors after that, put on sunscreen if you want. Just be sure to get morning or later afternoon sun, avoid the sun at high noon and don't get a sunburn."

"If sunlight were really that bad for us, we'd be nocturnal creatures like mice," says Gasparro. He notes that there is no one-size-fits-all answer to how much sun is enough. "Do you burn or do you tan? What's your family history of skin cancer?" You have to make your decisions based on that information, he says. "I don't think we should turn people into hermits."

Nissa Simon is the author of two books and many articles about health.