Pratyahara means drawing back or retreat. The word ahara means "nourishment"; pratyahara translates as "to withdraw oneself from that which nourishes the senses." In yoga, the term pratyahara implies withdrawal of the senses from attachment to external objects. It can then be seen as the practice of non-attachment to sensorial distractions as we constantly return to the path of self realization and achievement of internal peace. It means our senses stop living off the things that stimulate; the senses no longer depend on these stimulants and are not fed by them any more.
In pratyahara we sever this link between mind and senses, and the senses withdraw. When the senses are no longer tied to external sources, the result is restraint or pratyahara. Now that the vital forces are flowing back to the Source within, one can concentrate without being distracted by externals or the temptation to cognize externals.
Pratyahara occurs almost automatically when we meditate because we are so absorbed in the object of meditation. Precisely because the mind is so focused, the senses follow it; it is not happening the other way around.
No longer functioning in their usual manner, the senses become extraordinarily sharp. Under normal circumstances the senses become our masters rather than being our servants. The senses entice us to develop cravings for all sorts of things. In pratyahara the opposite occurs: when we have to eat we eat, but not because we have a craving for food. In pratyahara we try to put the senses in their proper place, but not cut them out of our actions entirely.
Much of our emotional imbalance are our own creation. A person who is influenced by outside events and sensations can never achieve the inner peace and tranquility. This is because he or she will waste much mental and physical energy in trying to suppress unwanted sensations and to heighten other sensations. This will eventually result in a physical or mental imbalance, and will, in most instances, result in illness.
Patanjali says that the above process is at the root of human unhappiness and uneasiness. When people seek out yoga, hoping to find that inner peace which is so evasive, they find that it was theirs all along. In a sense, yoga is nothing more than a process which enables us to stop and look at the processes of our own minds; only in this way can we understand the nature of happiness and unhappiness, and thus transcend them both.