The passage through which air travels from the nose and mouth to the lungs. The upper airway runs from the nose to the epiglottis. When it’s open, air flows freely and you breathe easily; when it’s constricted, airflow is restricted, disrupting breathing and sleep.

A molecule produced in the nasal passages and released when you breathe through your nose. It helps widen blood vessels and improves how much oxygen your blood can absorb, supporting better circulation and energy. Breathing through the mouth bypasses this benefit.