Pranayam means control of pran or vital force. According to the sage Patanjali it means controlled breathing which includes deep inhaling, exhaling and retention of breath. Pranayam occupies a central position in the Indian yogic system; it is said that liberation of soul is achieved through proper Pranayam and meditation.
Modern medical science has shown unequivocally that Pranayam has benefits for both mind and body. However the exact mechanism of how it works remains a mystery. Recent research has shown that nanoparticles (particle size of 10-30 nanometers which are almost 10-20 times smaller than those emitted in cigarette smoke), can directly reach the brain through nose breathing and bypass the blood-brain-barrier (BBB). This process may throw some light on how Pranayam affects the mind and body.
Medical researchers discovered for the first time in 1941 that small amounts of fine particles that were inhaled through the nose could be lodged in the brain by breaching the BBB. However this field of research remained dormant until the 1990s when scientists, alarmed by rising environmental pollution, revisited the early research and started discovering the harmful effects of toxin invasion of brain through breathing.