Despite repeated warnings and availability of data suggesting strong linkage between exposure to the sun and skin cancers, people across the world still uphold the belief that exposure to the sun can be beneficial in many ways than one. To understand why, let’s take a rewind through what made sun exposure an acclaimed form of therapy. 

The story behind a Nobel Prize

When necessity become the mother of invention, there is nothing much that can stop a man from creating history. A doctor by profession, Niels Ryberg Finsen himself suffered from a rare disease which left him drained to pursue his vocation. It is then that he began noticing how sunlight can be beneficial in certain health problems. As a result he scientifically developed Heliotherapy (therapy using sun’s radiations) for potent diseases-smallpox, lupus and tuberculosis, a monumental work that brought him the highest accolade -The Nobel Prize in 1903.

Understanding the untapped potential of this emerging form of cure, Dr.Auguste Rollier, a Swiss physician established solar bathing clinics throughout his region in the high altitude regions. He started applying intense solar radiation for the cure of skin, skeletal and pulmonary conditions. From there extended an era of solar therapy until it faded out with the discovery of much more potent anti-microbial therapies.

What are the benefits of Sun Exposure?

• At least a thousand genes in the body related to metabolism, bone health and neuro-muscular transmission are thought to be controlled by the active form of the sunshine vitamin-Vitamin-D : 1,25-di-hydroxy-vitamin. Unlike other vitamins, this vitamin is synthesized in the body by a photosynthesis action when body is exposed to a fair share of UVB (Ultraviolet rays B) rays.This fair share varies according to different parameters.
• Studies indicate that forms of cancer like-breast/prostate/colo-rectal, are linked to low levels of vitamin D in the body. So, sunlight considered a potential cause for skin cancer, in adequate amount, might be beneficial in preventing other forms of cancer. 
• Occurrence of Type 1 diabetes , Type 2 diabetes and cardiovascular diseases that often go hand-in-hand also have been linked to low vitamin D levels related to limited sun exposure.
• Good for regulating blood pressure to desirable levels in hypertensive patients.
• Development of auto-immune diseases like multiple sclerosis and rheumatoid arthritis has been found to have greater susceptibility to low levels of sunlight exposure than vitamin D levels in the body.
• Reduces obesity.
• Inadequate exposure to the sun is also a strong triggering factor for decline in cognitive conditions like Alzheimer’s disease in future.
• Sunlight is beneficial for the secretion of serotonin and melatonin hormones in the body whose regulation is closely associated to depression, mood swings and Seasonal Affective Disorder (SAD).
• The immuno-suppressive action of sunlight is found to act beneficially in autoimmunity problems.

Over-exposure hazards

• The greatest hazard is obviously skin cancer.
• Apart from cancer sunlight exposure can cause sunburns or polymorphic light eruptions. 
• They may cause premature aging and wrinkling of the skin and lead to liver spots or actinic keratosis kind of problems of the skin.
• They also affect the eye in the form of inflammation/outgrowths in the eye/cataract/melanomas in the eye.

All of these hazards are attributed to UVR exposure. But UV rays make up only a small portion of the sunlight we receive. 

It would be interesting to note that UV rays make up only approximately 5% of the solar radiation. The UV rays are categorized into three depending on their differences in wavelength and energy levels.

1. UVA : Constitute 95% of the UV rays reaching the earth in mid-day. Linked mainly to long term skin damage they also have been reported to cause indirect damage to skin cell DNA. Also causes skin cell aging.
2. UVB: 5% of solar radiation reaching earth’s terrain in mid-day. Major link to skin cancers and sun burns. Filtered to a certain extent by the ozone layer.
3. UVC: Strongest in terms of energy and therefore filtered by the ozone layer disallowing its entry to the earth’s surface.

sarva dharmeṣu madhyamaḥ

Adequacy is the watch-word. Therefore, take cue from these bullets to decide how much sun exposure is adequate for you and enjoy your fair share of sunlight.

• Though there are individual variants,to standardize,12 -15 minutes of exposure with the sun in its highest intensity which is between 11 am to 3 pm,two to three times a week have been accepted. (Subjected to change according to weather reports).
• Time of year and your geographical location should also be considered patiently.Near the tropics,for instance exposure will be usually intense and time period may be shortened. 
• Dark skinned people require more number of exposures to match the vitamin D levels produced in their fair skinned counterparts when both are exposed for the same time period.
• The UVR absorbed can be limited by your clothing.
• Short and frequent exposures are safer than longer exposures unless as part of therapies meted out by experienced physicians.
• If you have a history of sun burns or photo-sensitivity exposure needs to be re-considered and seek medical advice for the same.
• Exposure is not a substitute for Vit D supplements for high risk groups like pregnant women.
• Periodic testing of Vit-D levels can be considered with medical advice.

Ātapa sevā : Sun exposure in Ayurvedic parlance

Ātapa sevā is a unique form of therapy in the ancient medical scenario. Ancient culture held the Sun God in great reverence and awe and considered it as an immaculate healer too. Ayurveda is no exception and recruits it mainly for the purpose of inducing sweating in the body, a way of cleansing the body channels.

Ātapa sevā finds place especially with regards to the treatment of skin diseases in Ayurveda wherein you can find formulations after whose application the patient is required to expose himself to the sun for a short while. However the physical strength of the patient is a key factor that decides whether its to be administered or not. 

So, let your life also be filled with the warmth of the sunshine vitamin.