It promotes heart relaxation and the cardiovascular functioning because inversions slashes strain on the heart.
While in headstand, de-oxygenated blood is able to flow more easily from the extremities to the heart.
This asana even improves concentration, reduces anxiety and stress. This is because the flow of fresh oxygenated blood is soothing from the heart to the brain.
While in headstand, the brain collects a larger amount of blood than regular for a fixed period of time. This rejuvenates the neurons and protect against atrophy.
Performing headstand not only cleanses the body but also stimulates endocrine system, the pineal and pituitary glands which play a major role in balancing cell metabolism. It has a calming effect which helps to develop emotional stability. It also boosts the memory power and strengthens the immune system by promoting the circulation and drainage of lymphatic fluid. The reverse flow of the blood in the legs promotes tissue rebuilding. The weight of the abdominal region on the diaphragm encourages deep exhalation so that larger amount of carbon dioxide, toxins and bacteria are removed from the lungs. Cleanses and massages the internal organs.
Warnings:
It should not be practiced by people who have high blood pressure, heart disease, chronic catarrh, kidney problems, impure blood or weak blood eye vessels.