Heat is produced to maintain warmth in the boy. Except for atomic energy and God's creation of the world, we normally think of energy as being transferred from one state to another - neither created nor destroyed. The fact that light was the first thing created during creation week is evidence of its environmental importance. Its benefits are so clear that one can understand why so many throughout history have worshipped the sun. The remaining one percent is made up of cosmic rays, gamma rays, x-rays, radio waves, and electric waves.
Sunlight helps purify the environment by killing germs.
UV is also responsible for the production of vitamin D in the skin. Vitamin D is needed in calcium metabolism and bone production. As skin grows thinner in old age, the amount of vitamin D produced is less. Sunshine has been shown to make neutrophils more efficient at ingesting germs and to increase the number of lymphocyes in circulation, thus strengthening the immune system. It tends to normalize blood pressure and decrease blood cholesteral.