The upside of catching some rays

Posted Monday, Apr. 07, 2014  comments  Print Reprints
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Tips for healthy sun exposure

• Discovery Health reports on research that shows morning sunlight is best because that’s when our body clocks are the most responsive to the sunlight. Direct sun is better, as glass windows and windshields block UVB rays while letting in UVA rays, which can be harmful.

• Researchers say we should try for at least 15 minutes of undiluted sunshine three times a week, although exposure doesn’t have to be everywhere. You can still protect your face and soak up the vitamin D benefits by exposing other parts of your body, such as arms, knees or ankles.

• Certain health advocates have begun promoting the theory that it takes 48 hours for the vitamin D formed on the skin’s surface after sun exposure to “soak in.” Still others claim that most vitamin D production occurs at a cellular level, so bathing or not bathing after sun exposure is a moot point.

• It is impossible for vitamin D toxicity to result from too much sun exposure, researchers say. For humans seeking natural sources of vitamin D, 10 to 15 minutes of sunshine a day is more than adequate if you’re light-skinned, while dark-skinned individuals can handle up to three hours of sun exposure.

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By the time spring spreads its warm wings and we find ourselves happily swapping the sweaters for sandals, many worshippers of the Texas sun also have hightailed it to the store for a fresh bottle of sunscreen to renew our slather-up-before-stepping-outside regimens.

Although the onslaught of warnings about the dangers of too much sun — from wrinkles and sun-damaged skin to the health risks of skin cancer — are hard to ignore and undoubtedly valid, they also spread a cloud of uncertainty over equally meaningful reports regarding enormous health benefits linked to catching a few rays.

To get a tad technical: When sunlight hits your eyes, the optic nerve sends a slow-down message to a gland that produces melatonin, a hormone that helps us sleep. The secretions decrease until the sun goes down. In contrast, exposure to ultraviolet rays increases secretions of serotonin, a hormone connected to feelings of happiness and wakefulness.

Sunlight’s ability to boost the body’s vitamin D supply is the most notable benefit of exposure, and the National Institutes of Health (NIH) says at least 1,000 genes — controlling every tissue in the body — have connections to vitamin D3 regulation.

Through the years, scientists have cited healthy supplies of vitamin D in bone growth and the promotion of bone health, as well as the prevention of illnesses such as breast and colon cancer, inflammation, multiple sclerosis, seasonal disorders and depression.

Responding to the gravitational pull of our planet’s life-giving star is likely DNA-deep in the human psyche, and, apparently, it’s not such a bad thing. Here are a few reasons why:

Mood enhancement

NIH researchers have documented the positive correlation between the development of serotonin and sunlight, and noted that the turnover of serotonin in the brain is lowest during winter months when sunlight exposure is more limited, and consistently higher in warm months when exposure is increased.

Seasonal affective disorder (SAD) is a type of depression directly attributed to a shortage of sun exposure. According to the American Academy of Family Physicians, it affects 4 to 6 percent of people worldwide, with residents in northern latitudes and areas like Alaska (where sunlight is scant in the winter) suffering at much higher levels than those in southern latitudes.

Women between the ages of 20 and 40 also appear to be affected more frequently than men.

Human beings have likely struggled with it since ancient times, a fact that researchers say may explain why so many cultures time major celebrations around the shortest day of the year — and that these celebrations involve lighting candles.

Better sleep

Typically, the human circadian rhythm keeps us physically and emotionally charged during the day; slowed down and sleepy at night. According to the National Institute of General Medical Sciences (NIGMS), daylight exposure is vital to maintaining a normal circadian rhythm.

A recent study published online as a supplement to the journal Sleep found that workers in offices with windows slept an average of 46 more minutes per night than their windowless peers, tended to be more physically active and reported having a better quality of life in general.

Similarly, a 2012 neuroscience study determined that those who had six hours of sunlight exposure during the day were more alert in the evening.

Possible cancer-fighting properties

Researchers at the Moores Cancer Center at the University of California, San Diego have linked low vitamin D levels to greater risks of colorectal and breast cancer. According to the studies, raising the vitamin D serum levels is a factor in cancer prevention.

Lower blood pressure

In a recent study conducted at Edinburgh University, dermatologists studied the blood pressure of volunteers while exposed to UV and heat lamps and found that skin that is exposed to UV rays releases nitric oxide, a compound that lowers blood pressure.

In one session, the volunteers were exposed to both light sources and in the other session, the UV rays were blocked and only the heat was allowed to affect the skin. The results of the study showed a significant drop in blood pressure after exposure to UV rays for an hour but not after the heat-only sessions.

It is important to note that the volunteers’ vitamin D levels were unaffected in both sessions.

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