These reactions increase allergic symptoms and causes further hyperventilation. This further weakens the immune system so colds and flus are more prevelent and have stronger impact on the body. Correcting one's breathing leads to a general improvement in the body's natural immune response. Carbon Dioxide and the Nervous System - Stress, Anxiety and Panic Attacks Stress, anger, anxiety or excitement can create a state of sympathetic nervous system arousal. This causes one's heart rate and one's breathing rate and volume to increase.
Asthmatics commonly experience acute asthma at times of emotional reactions.
Working with breathing can be a highly effective way of controlling stress. Reducing one's breathing reduces excitation to the nervous system and produces a feeling of calm. CO2 is also crucial for the release of oxygen from heamoglobin to the tissues. Low CO2 levels mean one can have high oxygen concentration in the blood but poor release for oxygenation. Healthy, strong people breathe less at rest and during sleep but they can breathe deeply and get as much air as they need when they exert themselves or just want to take a deep breath.