“Pranayama is to yoga as the heart is to the human body.” – BKS Iyengar
Pranayama, or the fourth limb of yoga, is the practice of extending prana through the breath.
Pranayama comes after asana (poses) and before pratyahara (or withdrawing of senses) in the eight limbs of yoga, possibly because it's the yoga poses that teach us control of our breath and then the breath that allows us to withdrawal from our senses and eventually achieve samadhi.
In Ashtanga yoga, we use ujjayi breathing or an ocean breath during our yoga practice. By keeping the mouth shut and breathing in and out through the nose, we constrict our throat to make our breath even, making a noise that is sometimes called an ocean breath. According to EkhartYoga, pranayama encourages our mind to rest and allows us to better focus on the present moment.
In the Yoga Sutras, Pantanjali says the practice of pranayama draws away a veil from the mind and increases clarity. The mind becomes ready for deep meditation. When we have more prana, we bring a lot of benefits to the mind and body, including:
strengthening the respiratory system
increasing GABA (a neurotransmitter our bodies make naturally to calm us)
relieving chronic stress
improving parasympathetic nervous system
Want to try pranayama? Check out this 20-minute YouTube video by Bharti Yoga.