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Grandma Was Right: Sunshine Helps Kill Germs Indoors

Summary by Dr. Joseph Mercola

There was a time not so long ago when one prescription doctors would give their patients was to take a sun bath, or at the very least, to open the windows and let the sun shine in — some of the same advice that our grannies used to give. Now, even though you’d probably be hard-pressed to find a doctor who prescribes sunlight, our grannies would probably be pleased to know that scientists have found that opening the windows was the right idea.

As reported by NPR, researchers found that rooms exposed to daylight have fewer germs. Specifically, sun-exposed rooms have about half the viable bacteria as dark rooms.

It’s puzzling how the modern world came to vilify the sun and all it can do for you, but one thing is certain: Researchers now say that 85 percent of children in industrial cities and well over half of adults suffer from vitamin D deficiency. In other words, they don’t get enough sun in their daily lives, inside or out.

Part of this is due to our desire to contain ourselves in a temperature-controlled environment 24/7, with the windows closed. Another factor is that health officials are constantly reminding us to slather up with sun-blocking creams whenever we do venture out. The idea is to lower your risk of skin cancers, but it flies in the face of research showing that outdoor workers actually have a lower incidence of melanoma, the most aggressive form of skin cancer, than do indoor workers.

The fact is sensible sun exposure has many health benefits, not the least of which is letting some light into a darkened room. For you, personally, it takes exposure to real sunlight for your body to naturally produce the vitamin D levels that keep you healthy.

If you need more proof, mounting research confirms that sun avoidance may be at the heart of a large number of health problems. In fact, humans appear to have a lot in common with plants in this regard — we both need direct sun exposure in order to optimally thrive. To back up this claim, researchers did a laboratory study using cells in petri dishes, showing that exposure to blue and ultraviolet (UV) light increases T cell activity — white blood cells involved in immune function and fighting infections.

This certainly isn't the first time sunlight has been shown to produce biological effects that are important for good health, though. Other health benefits of sun exposure include the following:

  • Spending time in bright midday sun helps anchor your circadian rhythm, which is important for optimal sleep.
  • Aside from being mood-boosting, sunlight exposure also helps lower high blood pressure and reduces your risk for heart disease and cancer.
  • Sunlight also appears to alter genetic expression. Cambridge University scientists recently showed that the expression of 28 percent of the human genetic make-up varies from season to season, and some of these changes affect your inflammatory responses.
  • And, finally, as mentioned in the featured article, both UV light itself and the vitamin D produced when your skin is exposed to it have potent antimicrobial effects. While vitamin D increases production of naturally occurring antimicrobial peptides that destroy the cell walls of viruses and bacteria, UV light also increases blood levels of infection-destroying lymphocytes (white blood cells).