“

Normal breathing is a balance between breathing in oxygen and breathing out carbon dioxide. When you upset this balance by exhaling more than you inhale,( it) causes a rapid reduction in carbon dioxide in the body, low carbon dioxide levels lead to narrowing of the blood vessels that supply blood to the brain. This reduction in blood supply to the brain leads to symptoms like lightheadedness. This is why it is often recommended to start slowly and practice three to four cycles at a time until you are comfortable with the technique.