Why do I sometimes feel dizzy in a breathing exercise?

Dizziness is normal in breathing exercises where deep, rapid inhalations, or hyperventilation, is part of the practice. Hyperventilation causes carbon dioxide level in the blood to drop, which causes blood vessels to constrict. And this results in vessels carrying less oxygen to different parts of the body. Very counterintuitive, right? You’d typically expect more oxygen to get around when you breathe more, but a certain level of carbon dioxide is necessary for circulation to occur normally. If you feel too uncomfortable, you may take a break and continue when the feeling passes. But keep in mind that sensations such as tingling and light-headedness are also very common in deep breathing exercises.