"Whereas slow breathing soothes, overly rapid breathing can induce feelings of stress and anxiety. This phenomenon is used in behavioral therapy sessions to train anxious patients to confront their emotions directly. By deliberately hyperventilating, patients artificially trigger an unpleasant anxiety, which they get accustomed to feeling and learn to put in perspective. This technique also enables them to see that poor breathing habits amplify their fear."

https://www.scientificamerican.com/article/proper-breathing-brings-better-health/