Once upon a time, sunlight was considered a divine power. Today, sunlight has been classified as a Class 1 carcinogen by the World Health Organization (WHO). In ancient times, sunlight was honored for its healing qualities. In modern times, sunlight is blamed for disease, and people are encouraged to avoid exposure to the sun.
Dr. Alexander Wunsch is a photobiologist and CEO of Medical Light Consulting in Heidelberg, Germany. In a recent article, Dr. Wunch looked at sunlight from the historical and medical perspective. He says,
Nowadays, sunlight is not fashionable anymore. Some experts even try to ban the tan, others work on restrictions, the U.S. Surgeon General issues a call to action on UV and tanning. How can we deal with these dark clouds in a formerly sunny sky?
Knowing more details about the past can help us to adjust and normalize the extreme positions of the ‘no sun policy’ advocated by the World Health Organization (WHO), the anti-cancer associations and many dermatologists.
The first written report of using sun for medical purposes came from Herodotus in the 6th century BCE. The ancient Egyptians used the sun to combat germs, and it was part of medical treatment by early Arabians. Up until the 1950s, sunlight was employed to treat tuberculosis and rickets.
Dr. Wunsch says all plants and animals instinctively understand how much sun is good for them. He explains:
Plants close, or turn away their leaves, until their molecular light harvesting zones. Animals seek the shadow and protect themselves by wearing fur.
While animals are protected by sunlight from fur, humans must rely upon their skin. Fortunately, human skin has developed complex ways to protect itself from solar radiation. Over time, with gradual exposure to the sun, the skin thickens. This thickening actually changes the optical properties of the epidermis. This solar acclimation can take up to four weeks, as the keratinocytes and corneocyte skin layers are saturated with melanin pigment. Your skin also uses leftover DNA in the keratinocytes in the spinous layer of skin as a natural sunscreen.
You already know that sunlight is necessary for your body to produce vitamin D. According to Dr. Wunch, there are other important benefits, as well.
Sunlight induces coordinated endocrine adaptation effects. It affects sympathetic and parasympathetic activity, and is a major circadian and seasonal stimulus for the body clock … Our system, via the eyes and via the skin, detects the colors of the light in the environment in order to adapt the hormonal system to the specific needs of the time and place.
It’s different if we are sitting under the sun in the desert, or if we are sitting under a leaf roof or under a tree somewhere in the woods. The colors around us tell, through the eye, to our brain, to the mid-brain [and] to the hormonal steering centers, what happens around us and what is to do in order to cope with this particular situation.
Increasingly, scientists are recommending that public health would best be served by educating people as to the optimal amount of sunlight they need, rather than encouraging them to shun the sun entirely.