The word Nadi comes from the Sanskrit root  meaning “channel”, “stream”, or “flow”.

They are pathways of pranic, mental and spiritual currents, which form a network throughout the physical body. This network provides energy to every cell, and every organ through their vast network, carrying prana back and forth in every direction. There are 72,000 Nadis in human body.

The nadis originate in the muladhara, or root chakra and follow the length of the spine, traveling in and out of the chakras, or energy centers and the Ida Nadi (Chandra nadi) ends at the left nostril, the Pingla (Surya Nadi) at the right nostril and Sushumna at the crown. Freeing the nadis of blockages promotes physical, mental and spiritual health by allowing the life force energy – Prana to flow smoothly throughout the body.

Fourteen of the 72,000 Nadis are considered important and out of them 3 are most important:

Pingla – Also called the Surya nadi as it is related to solar energy, represents the qualities associated with the sun: Physical activities, masculinity, extroversion, logic, strength, vitality, efficiency, the left brain and right body. It corresponds to the sympathetic nervous system which stimulates all the external activities. It is stimulated by the right nostril.

Ida – Also called the Chandra nadi as it is related to the lunar energy represents the qualities associated with the moon: Mental activities, creativity, retrospection, passivity, introversion, concentration, femininity, right side of the brain and left side of the body. It corresponds to the parasympathetic nervous system which reduces the heartbeat, constricts the blood vessels, and slows the respiration so that the individual becomes calm. Its stimulated by the left nostril.

Sushumna is attribute-less, it has no quality of its own. It is like an empty space. If there is empty space, it imbibes anything. It changes according to the ripples in the environment. Once energies balance in the Sushumna, one attains Vairagya “Raga,” means color. “Vairag,” means no color. So no matter how the Pingla nadi or Ida nadi may fluctuate or be affected by the outside and attempt to cause disturbance inside, when Sushumna Nadi is firm and strengthened one achieves an internal balance and is unaffected  by any outside fluctuations.

These energy currents flow and operate alternately and the current that is flowing at any particular time is determined by the flow of breath in the nostrils, which alternate approximately every one to two hours.  Ideally, the right nostril is dominant during the daytime and the left at night. Both nadis affect our health and are directly affected by the movement of both the sun and moon. 

The flow of prana in these two nadis is involuntary and unconscious unless we manage it with yogic practices. So the various pranayams help to regulate them and benefit our health.

Nadis and sleep:

There are times during the day when one is tired or feels sleepy, this is an indication of the Surya nadi needing attention (through pranayama).
At night when one is unable to sleep or is feeling very active it is the time to give attention to the Chandra nadi (through pranayama).

Also when we sleep on our left side after a meal, the armpits get compressed, the nadis are stimulated and the right nostril is activated. This nadi helps heat up the body and stimulates digestion. Physiologically the shape of the stomach is like a C curved toward our left side,  so that sleeping on left side after meal makes the functioning of the stomach easier.
On the other hand after Shavasana practice, we turn over on the right side and lie down for a while before we sit up for pranayama – because this stimulates the Chandra nadi the left nostril  which is more cooling and calming.

When we sleep on time at night, the right nostril switches to the left and is then functioning well. And the right nostril will automatically be predominant first thing in the morning after a good night’s sleep. These systems have been intricately studied over many years; The sunrise affects certain hormonal patterns. When we follow the rhythm, our health automatically improves. When one stays up late at night, our strength, ability to focus, creativity and deep energies are severely affected. It is important that we align our day early in life, in tune with nature.