Increased airway resistance can induce snoring and sleep apnea, and nasal obstruction is a common problem in snoring and obstructive sleep apnea (OSA) patients. Many snoring and OSA patients breathe via the mouth during sleep. Mouth breathing may contribute to increased collapsibility of the upper airways due to decreased contractile efficiency of the upper airway muscles as a result of mouth opening. Increased nasal airway resistance produces turbulent flow in the nasal cavity, induces oral breathing, promotes oscillation of the pharyngeal airway and can cause snoring.