For thousands of years, humans have understood breathing has a powerful influence over our physiological and psychological wellbeing. But many people still find it difficult to understand the link between breathing and its impact on our body’s physiology and stress levels.
Research has shown the way we breathe has a powerful effect on how stressed we feel. When we feel stressed, one of the physiological changes that occurs is activation of the sympathetic nervous system (fight/flight response) and an immediate increase in respiration switching from slow, abdominal breathing to faster, shallower, chest breathing.
via Breathing Correctly.