Ask the Doctors

Dear Doctor: It seems as if people, without fail, say they feel better when the sun is shining, yet the medical community seems to tell people to stay away from the sun. The sun is shining as I ask: Is there some conspiracy here?

Dear Reader: We wouldn't say there's a conspiracy afoot when it comes to advice regarding the sun and sunshine, but there certainly are plenty of inconsistencies. On one hand, there's the indisputable link between exposure to the sun's rays and a range of skin cancers. On the other hand, there are all of the ways that the availability of sunlight is tied not only to mood, but to metabolism as well. When taken together, the various warnings and admonitions about getting too much or too little sunlight and sunshine add up to a snarl of contradictions.

On the "less sun" side of the equation are the physical changes that exposure to sunlight can cause to the skin. In the short-term, there's tanning, which in our culture is associated with health and well-being. However, the physiological changes that cause the skin to get that sun-kissed glow are actually signaling that damage is taking place at a cellular level. Many of the signs of aging, including wrinkles, dark spots, splotches and sagging, are due to sun exposure. Ultraviolet light, a specific spectrum in the sun's rays, damages fibers in the skin known as elastin. These are a key component in keeping your skin taut, flexible and youthful. Of even greater concern is the fact that sun exposure raises the risk of a variety of skin cancers, some of them aggressive and potentially fatal.

But you're right -- sunlight is crucial to our emotional and physical well-being. Our circadian clocks, which oversee functions like sleep-wake cycles, mood, appetite, energy levels and hormone production, rely on the rhythms of the sun to stay in sync. Vitamin D, known as the "sunshine vitamin," is manufactured by the body through a process that is triggered by sunlight on the skin. We know that you need vitamin D to build bone. But the fact that many of the tissues and organs in the body have vitamin D receptors suggests it's important to other physiological functions as well.

So what's the sweet spot when it comes to getting enough sun, but not too much? If you're not getting adequate vitamin D from supplements or fortified food, spend 15 to 30 minutes per day in direct sunlight. And because sunscreen has been found to block 90 percent of vitamin D production, leave your skin unprotected for that time. (But be sure to put on the sunscreen and cover up with long sleeves and a hat once the vitamin D time is over.)

When it comes to mental well-being, years of research show that spending time outdoors is good for us. Sunlight plays a role, and so does the length of available daylight. We agree with you that it's important to take the time each day to get out of the house or workplace and spend some time outside.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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