Mouth breathing refers to the habit of breathing through the mouth rather than the nose. Frequent mouth breathing is normal, but chronic mouth breathing can lead to tooth decay, bleeding gums, and gum disease. Mouth breathing can also worsen sleep apnea.

When people breathe through their mouths, they bypass the nose’s natural filtering, warming, and humidifying functions. Therefore, the air entering the respiratory tract is colder, drier and less filtered. This can lead to increased inflammation of the upper respiratory tract and contribute to airway obstruction.

Mouth breathing can also affect the position of the tongue and jaw, and this can lead to further airway obstruction during sleep. The lowered position of the tongue and the lack of support from the closed lips can cause the tongue to fall back more easily and partially block the person’s airway.