How is breathing regulated?

The transport (afferent) of stimuli from the nerves that regulate breathing are in the nasal passages. The inhaled air passing through the nasal mucosa carries the stimuli to the reflex nerves that control breathing. Mouth breathing bypasses the nasal mucosa and makes regular breathing difficult. During sleep, it predisposes one to loud snoring and irregular breathing and can lead to a serious condition called Sleep Apnea.