1. Increases Stamina and Strength and Promotes Good Posture
Headstand builds strength in the neck and shoulders as well as the abdominals and upper spine.

2. Improves Cardiovascular Functioning
Inversions reduce strain on the heart which normally works against gravity. While in headstand de-oxygenated blood is able to flow more easily from the extremities to the heart.

3. Strengthens and Massages the Lungs
Due to gravity, the lower parts of the lungs receive more fluids which cause the tissue in the lower lungs to be more condensed. As a result, when we inhale air moves more freely to the upper part of the lungs. When we invert, blood moves to the upper part of the lungs facilitating a more efficient oxygen-blood exchange. Also, the weight of the internal organs massages the lungs increasing vital capacity as the lungs learn to breathe against the added weight.

4. Stimulates the Digestive System
Headstand increases digestive fire boosting energy and increasing body heat. Internal organs, particularly the intestines, are cleansed by reversing the pull of gravity and releasing congested blood in the colon.

5. Improves Concentration and Balance
In headstand, fresh oxygenated blood flows more freely from the heart to the brain. The brain receives a greater amount of blood than normal for a fixed period of time. This helps rejuvenate the neurons and guard against atrophy. People often report a sense of clarity after doing headstand.

6. Stimulates the Endocrine System
Practicing headstand stimulates the pineal and pituitary glands which are important in regulating cell metabolism.

7. Calming Effect — Helps Cultivate Emotional Stability
Yogis have long believed that headstand has a calming effect and helps to stabilize moods and I have found this to be true for me.

8. Strengthens the Immune System
Headstand helps improve the circulation and drainage of lymphatic fluid. The lymphatic system is composed of one-way valves that keep the lymph fluid moving towards the heart. Turning upside down helps to stimulate the entire system and facilitate the movement of lymphatic fluid from the lower extremities.

For safety reasons, I would strongly recommend learning headstand from an experienced teacher who can help and guide you.