No child should persistently breathe through an open mouth. It's not harmless. Mouth breathing is probably one of the worst habits that any child can develop. We know that between 25 to 50% of studied children are persistently breathing through an open mouth, both during wakefulness and during sleep. No child reaches their full genetic potential if they are using their mouth to breathe. Why? Find out in this video created by Patrick McKeown, Buteyko Clinic founder and instructor to thousands of adults and children.