Alternate nostril breathing is known as Nadi Shodhana, which translates to 'channel purification' in Sanskrit. It is traditionally believed to harmonize the flow of prana (vital life force) by balancing the lunar (cooling, intuitive) and solar (warming, active) energies associated with the left & right nostrils. It's  said to balance the left & right hemispheres of the brain and regulate the autonomic nervous system, shifting the body into a calm, parasympathetic state to create mental clarity.

PHYSIOLOGICAL RESPONSE

By alternating airflow between the nostrils, you regulate oxygen and carbon dioxide levels through slow, conscious breathing, which helps to activate the parasympathetic nervous system and effectively calm your limbic system (the brain's emotional center). The practice modulates brain wave patterns in both hemispheres.

Body 

• Balances nervous-system activity 
• Improves lung function 
• Promotes relaxed awareness
• Enhances clarity & concentration 

Energetics 

• Harmonizes inner duality (lunar/solar, left/right hemispheres) 
• Steadies emotions 
• Creates mental spaciousness 
• Balances prana or chi

Avoid this technique if you have any kind of nasal congestion, cold, or severe sinus issues.