Ida, Pingada , Sushumma:
On either side of the spine there is an energetic nerve channel/ lifeforce or nadi : ida on the left and pingala on the right.
The prana or energy travels upward through the ida nadi. With this upward movement, the breath is automatically drawn into the lungs. As a result, the mind is drawn outward to the world of the senses. Its deity is Moon. The Ida is also called the nadi of the Moon. It is cool and has an element of “Tamas”. It regulates the human thoughts.
The energy then travels downwards through the pingala nadi. When the energy is going down, it is called apana rather than prana. This downward movement is accompanied by physical exhalation, and signifies a rejection of external circumstances. Its deity is Sun. The Pingala is also called the nadi of the Sun. It is warm and has an element of Rajas. It regulates energy or lifeforce in human body.
One manifestation of this cycle is the association of inhalation with excitement and happiness, and exhalation with defeat and depression. Happiness and sadness must always follow each other when the cause of each is external circumstances, which are always changing.
However, through pranayama techniques a person can instead redirect the energy through the deep spine in between the ida and pingala, called the sushumna. When the level of energy in the sushumna reaches the top of the spine and goes into the spiritual eye, or sixth chakra, one becomes enlightened. The deity of Sushumna is Fire. Of all the Nadis Sushumna is the most important and known as the Brahmanadi. IT has been named as “Saraswati” or “Shanti”nadi. This nadi imparts wisdom. It is neutral in nature.