This should be a no brainer. Why should you face the sun early morning while doing yoga or while praying the Sun?

Obviously to make the body absorb sunlight early morning time when its most beneficial. The early morning sunlight, helps to activate the Vitamin D in the body which is rare to be found in any food we consume. 

This Vitamin D then helps to absorb the Calcium into the right places like bones from the food that we have eaten.

So remember if you are popping those calcium tablets but not taking any form of Vitamin D, all that calcium will be flushed out every morning :).

Another thing to remember is that genetically Asians have least Vitamin D in the body even after exposure to the sun. So make the most of it by standing in front of the sun when doing your Yoga or even reading the newspaper! 

Vitamin D is also available in the powder form in the medical shops. It can be taken once every three months from 60000units to more depending on the lack of it in the body. (always check with your doctor).

Growing kids, women must have Vitamin D. Kids need it for their growing bones and women need it as their body is not great in storing calcium.

So when early people passed on this knowledge as a rule that all people must do Suryanamaskar in front of the sun with a tiny vessel of water poured slowly, they were making sure that ladies got enough sunlight to activate their Vit D for healthier bones.