Your Body on Sunlight: Beyond Sunburns and Vitamin D –

When we think about the sun’s effects on health, we think we have the plusses and minuses all sorted out: we need sunlight to stimulate vitamin D production, and too much causes sunburns and sometimes cancer.

But science shows us that soaking up those warm rays also affects our bodies and brains in other complex ways that transcend vitamin D and sunburns.

Read on to learn about some of the fascinating ways that sunlight’s UVA and UVB radiation can alter our health status—for worse and for better.

Altered Immune Function

Both UVA and UVB radiation suppresses immune function, which is a double-sided coin for overall health.

In the short-term, sun exposure increases the risk of developing certain infections, like yeast infections and cold sores.

But moderate sun exposure over time can protect us: scientists believe that changes in T-cell activity that occurs in our bodies during sun exposure may lessen our risk of developing autoimmune disorders.

Changes in Metabolism

Bright lights, including sunlight, change the way our bodies process energy.

Researchers at Northwestern University found that bright lights actually inhibited the effectiveness of insulin in our bodies, which in the long-run could increase our risk of metabolic diseases like diabetes.

But the data was nuanced: study participants who basked in bright lights in the morning fared better in terms of glucose metabolism and maintaining a healthy body weight than those who experienced the light in the afternoon.

What does this mean for us? It’s early to tell, but perhaps scheduling outdoor activities during the morning hours could help regulate our metabolism in ways that matter to our overall health.

Regulation of Sleep Hormones

Have you ever stayed up too late, focusing your bleary eyes on the TV when you knew you should be resting?

Morning sunlight can help, because it causes the sleep hormone melatonin kick in sooner as night approaches. That can help us feel ready for bed at a reasonable hour.

Morning sunlight and its power to regulate melatonin can also treat Seasonal Affective Disorder, PMS and insomnia.

Damage to Eyes

Sensitive eye tissue responds uniquely to sunlight. We squint in bright sunlight and our pupils constrict, which helps mitigate the intensity of sunlight in our eyes. Even with these adaptations, our eyes are still vulnerable to UV radiation.

Two types of temporary inflammation, photokeratitis and photoconjunctivitis, feel like a sunburn in the cornea and conjunctiva. (This uncomfortable inflammation thankfully resolves with no lasting effects.)

In the long-term, sun exposure can increase our risk of cataracts. The WHO estimates that 20 percent of the cataracts that individuals develop worldwide result from overexposure to the sun’s rays.

Changes in Mood and Brain Chemistry

Endorphins are nature’s opiates, and sun exposure boosts their presence in our bloodstream. (Maybe that’s why a day at the beach feels so great!) Sunshine also stimulate the brain to produce more of the neurotransmitter serotonin, which plays an integral role in maintaining a positive mood.

When it comes to sun exposure and the intricate way it interacts with our bodies, the old advice probably still stands: moderation is best. Get outside early, protect yourself from burns and do what you love to do in the sunshine, whether that’s gardening, swimming, playing ball or reading on the porch.


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