The Pranayama (rhythmic control of the respiration) teaches to control the breathing and the mind.
Pranayama literally means “control of vital energy”. We need to underline how the breathing and the cerebral activity are strictly linked.
Every time we feel agitated, nervous or angry, our respiration becomes short, every time we are relaxed and joyful, our respiration is relaxed and long, capable of inhaling a lot of air. The same way our emotional state has an effect to our respiration, our respiration has an effect on our emotional state. That means that if you concentrate keeping your respiration calmer, you will have a state of mind which is calmer and more relaxed.
Recently, researchers are testing and measuring the physiological effects correlated to the respiration. These effects influence the kind of cerebral waves produced by the brain during the meditation. The Pranayama includes a lot of techniques of respiration useful to the control of numerous physiological processes, such as the body temperature, the concentration, the digestive capacities, the resting period, the number of heart beats and others. For these reasons, the pranayama is used for therapies.
The choice of different rhythmic models for the deep and slow respiration, strengthen the respiratory system, calm down the nervous system and reduce greed. The mind is free and becomes a mean to concentrate. The aim of Yoga is to calm down the mind and control it, and the Yogi learns the Pranayama technique to dominate respiration, to master the senses, to reach the state of Pratyahara (withdrawal of the senses) and to start practicing dhyāna (meditation).