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04.08.2019 Feature Article

Sunlight And Health

The Good and the Bad of Sunlight Exposure
Sunlight And Health
LISTEN AUG 4, 2019

Sunlight promotes good health. Overexposure to sunlight could be harmful.

Let us start with the Health benefits.


Serotonin, a neurotransmitter, has been called the “happy hormone.”

Serotonin (5-hydroxytryptamine; 5HT) is synthesized from the essential Amino Acid (one of the building blocks for proteins that the body cannot make itself) called Tryptophan. Tryptophan is found in foods like Banana/plantain, Pineapple, Tomatoes, Dark-green leafy vegetables, Seeds, Oats, Soy foods, Nuts, Fish and Eggs.

Serotonin is a neurotransmitter (chemical messengers in the brain), that helps to regulate our mood, sleep pattern, appetite and social behaviors

Sunlight exposure increases Serotonin production in brain. Inadequate sunlight exposure leads to lower Serotonin levels which have been linked to Lack of sleep, depressed Moods, Anxiety, Phobias, Poor Memory, Irritability and Tiredness.

Exercise increases the production of, the Neuronal growth-protein BDNF. BDNF acts by increasing serotonin and dopamine levels in the brain.

Thus, walking (doing Exercises) in the sunshine helps to Relax us, Sleep better, Improve our Moods, and make us Smarter.


Children and Teenagers who spend more time outdoors are less likely to wear corrective glasses for near-vision/myopia. Children who tend to stay indoors develop eyeballs that are too long.

When the eyeball is too long, images refracted from the lens and cornea, do not reach the retina and the images become blurry.

Natural sunlight promotes the release of Dopamine in the Retina. Dopamine acts as stop signals to prevent an abnormal elongation of the eyeball during growth.

More and more kids are wearing corrective eye glasses nowadays.

We must encourage our Children, Adolescents and Teenagers to play outdoors instead of staying indoors with their eyes fixed on the screens of their mobile and fixed apps.


In the skin, UV-B light exposure, helps with the production of vitamin D

Just 15 minutes (30-45 minutes if you are very dark) of sunlight in the tropics, or in summer produces about 3000 IU of vitamin D, depending on your skin pigmentation and latitude.

Vitamin D helps us to develop and strengthen our bones. Vitamin D also help us to fight-off some cancers.

Among the cancers that have been associated with low vitamin D levels, and which show improvement with vitamin D supplementation are:

. Colorectal cancers, Breast cancers, Prostate cancer, Ovarian cancers, Pancreatic cancer and other diseases of the pancreas


The Sun emits radiations at different wavelengths. For our health, it is the Ultraviolet radiation (with wavelength 100-400nm) that we need to be concerned with. Ultraviolet radiation has been classified into 3 primary types

UVA wavelength 315-399 nm, penetrate the ozone layer freely, causes Skin aging and Wrinkling

UVB wavelength 280-314 nm partly absorbed by ozone layer, causes Sunburns, most Skin Cancers

UVC wavelength 100-278 nm completely absorbed by ozone layer; does not reach Earth surface.

Due to Ozone-layer and atmospheric absorption, only 5% of the UV rays are UVB; 95% is UVA.

Overexposure of the Eyes to UV light can lead to CATARACTS formation

Overexposure to UV light can lead to skin cancers: Basal cell carcinomas and Melanomas

  1. Skin pigmentation and sun-protection

There are 2 types of skin pigments: EUMELANIN and PHEOMELANIN. Both are produced in the skin from the Amino Acid Tyrosine). Absence of the enzyme, tyrosinase, that convert tyrosine to the skin pigments cause the affected persons to become Albinos

Eumelanin has Black to Dark-Brown pigmentation.
Pheomelanin, which contain sulfur atoms, has Reddish/Orange color pigmentation.

Eumelanin pigments are able to absorb UV light and block the UV photons from entering the deeper layers of the skin.

Pheomelanin skin pigments are unable to block UV light energies, and allow the formation of free radicals and cancer cells in the skin.

Dark-skinned people have more of Eumelanin; those with fair-colored skin have more of the Pheomelanin and are at higher risks for skin cancers and skin damage.


Everyone, especially those aged 50 years and over, could be at risk. Those who spend long hours in the sun especially between 10 a.m. and 4 p.m. are at increased risk. Those who have fair-skin/light skin color (they have more of pheomelanin than the protective eumelanin skin pigments) are also at increased risk for the skin cancers.

  1. We must enjoy sunlight in the early morning and late afternoons. Avoid the sun and stay in the shade between 10 a.m. and 4 p.m.
  1. Wear wide brim Hats (to provide shade to our heads and necks)
  1. Wear sun-protective eye-glasses
  1. Apply Zinc oxide 20% sunscreens regularly when going outdoors (zinc oxide blocks all UV light energies) Other broad-spectrum sunscreens with Sun Protective Factors (SPF) 15-50 are helpful.