SUNLIGHT:
Today the theme of celestial challenge by 
We humans have created many artificial sources to get light starting from Thomas Edison (1879) till now, but any light that has been created by bulb, have the advantages that a sunlight do?
GOD had not created anything useless or unimportant, everything in the world has some importance, just like the sunlight, it's not only to lighten up the world but also our body has some needs that is only fulfilled by the sunlight.
We get vitamin D and mutagen from Sun but we have created the medicines and are depending on the vitamin D present in our daily meal but that meal doesn't provide us the mutagenic effect. This is the major cause of increase in cancer ratio in the whole world that our life and working hours are scheduled in a way that we are unable to get proper sunlight . Also have positive effect on endorphin levels and protection against multiple sclerosis. Also have possible effect on eyes on association with the timings of melatonin synthesis.
NATURAL CAN NEVER BE REPLACED BY ARTIFICIAL