Mudras bring about improvement in our body through the rectification of certain elements deficient in our body. They produce energy, peace, and happiness for the body. Mudras also mold emotional aspects of the person. It has been seen and heard that many people have cured themselves through regular practice of hand Mudras. Mudras prevent negativity from harming the body and bring about fundamental revision.
Mudras are also used in prayers; they bring about cosmic awakening.
If not practiced religiously and regularly for the prescribed time you may not achieve the desired results. As through mudras the mind heals the body. The mind will heal slowly but surely. You will experience holistic changes as the mind heals the body.
http://www.healinglaya.com/mudras_i