The activity of our Autonomic Nervous System (A.N.S.) is regulated by the hypothalamus in the brain and a very fine functional balance is maintained in these two branches (sympathetic and parasympathetic) of our A.N.S. This balance can become disturbed due to a certain factors such as, emotions, overwork and hormones, etc. The Hypothalamus is an important center of the A.N.S. Which regulates many activities, for instance it determines the appropriate responses: "That is ok", "That needs immediate attention", or "Panic!" When the hypothalamus presses the panic button, it stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary, which acts on the adrenals to produce stress hormones, primarily adrenaline and cortisol. These hormones flood the body, enabling us to respond to the danger at hand. Yoga practice affects the activity of the hypothalamus in a positive way.

Book Title: The Brain Ref: ISBN 0-920269-32-x