Prana is the unmanifest energy of consciousness that permeates the universe and the manifest force of creation. Prana is our life force and pranayama (life force expansion and control/regulation) is the practice of building, moving and directing that energy via the breath using the concentration of the mind - as the breath is one of the 3 sources of (prana) vital energy in the body and a bridge between the body and mind. As our thoughts effect our breathing patterns (and prana) we can also control our thoughts by our conscious breath. Where the mind goes prana goes. When we breath consciously we are bringing our senses inward, guiding and controlling the prana which produces calmness, stillness, and effects us on subtle levels influencing our psychic and spiritual state which brings us to higher states of awareness - our pranic breath has inner wisdom and has subtle effects on our consciousness.
Pranayama (and advanced pranayama) with concentration methods exist amongst the many yogic traditions - serving specific purposes. Techniques may include guiding the prana in certain energy coordinates and may use bandha, mudra, mantra, nada, and bodily postures as well as conception. Higher yogic practices guide and focus the energy in the sushumna nadi (spinal channel) and specific energy centers. The Bandhas, Bodily Mudras and Kumbhaka are important elements to assist in unlocking potential and energy for our spiritual progress. The kumbhaka (pause/gap/retention) of breath assimilates the prana and stills the mind. The highest stage of pranayama is breathlessness or kevala kumbhaka, where the breath is naturally suspended without any effort and the yogi is in a state of absorption or samadhi. The Yoga Sutras technically define pranayama as the kumbhaka or "pause" in the movement of inhalation and exhalation.
As pranayama is the doorway to higher consciousness, pranayama practices also play an essential role for a healthy body and mind. Benefits include purifying the energy channels (nadis), oxygenating the blood, increasing blood flow to the brain, calming the mind and nervous system, cleansing toxins, helping digestion and strengthening immunity.
Pranayama was developed by highly advanced yogis through their inquiry and experimentation and connection to higher beings. They discovered through various methods of conscious breath control how it affected the physical and subtle bodies as well as how to access higher states of consciousness.
Many ancient texts reference pranayama and others are manuals that present pranayama techniques. To name a few - The Bhagavad Gita, Upanishads, Yoga Sutras, Hatha Yoga Pradipika, Gheranda Samhita, Hatharatnavali, Yoga Yajnavalka, etc. Texts that provide instruction only give basic guidelines and do not reveal the depth of the practices. Ancient yogic lineages in India and Tibet hold the wisdom and secrets to applying the techniques per tradition and deciphering sanskrit versus. One needs to study with a lineage to correctly apply any yogic technique. Pranayama techniques may be unsafe or cause discomfort if not correctly understood and taught by a knowledgeable teacher.
The wisdom and science of yoga has been kept alive for thousands of years by ancient yogic lineages. Modern science has been researching aspects of this wisdom and has recognized their benefits to our physical, mental and spiritual well-being. Yogic breathing is now being acknowledged to positively effect our consciousness and health. Many diseases and imbalances can be linked to improper breathing and our stressful lifestyle - and the power of the breath and it's healing properties are getting more recognized throughout the world. As the breath is getting more attention and new "breath" practices emerge, let's not forget the origin of breath science. This science has been transmitted by perfected beings who have transcended the mind through meditative insight and higher knowledge.
"Pranayama is the inner fire ceremony, purifying our thoughts, mind and life"