Should I breathe through my nose or mouth?

Nose for calming, mouth for energizing. Research published in the American Journal of Physiology found that nasal breathing increases parasympathetic contributions to heart rate variability and lowers diastolic blood pressure compared to mouth breathing. The nasal passages also warm, filter, and humidify the air, and trigger nitric oxide release, which helps dilate blood vessels. If you’re trying to activate and bring energy up (dorsal vagal state), mouth exhales can be useful because they allow faster, more forceful release. As a general rule for calming breathwork: nose in, nose out.