Chronic nasal congestion starts with mouth breathing, which activates accessory muscles in the upper chest. You limit or reduce the use of the diaphragm when using chest muscles. At night when you don’t use diaphragmatic muscles during sleep, the upper airway muscles become lazy and can collapse resulting in obstructive sleep apnea. Your brain tries to slow down the amount of CO2 exiting the body through the mouth which creates more mucus in the nose consequently creating more congestion. Allergy shiners are dark circles under the eyes caused by nasal and sinus congestion are often confused with being tired (dark bags under the eyes). Nasal congestion, allergies, and asthma can improve with myofunctional therapy.