Turbinates are bony structures inside your nose covered by mucous membranes. They help to regulate airflow through the nose and help to humidify and clean the air we breathe. The mucous membrane that covers the turbinates can shrink or swell in response to changes in blood flow. Things that alter blood flow such as lying down, certain foods, allergies, medications, hormones, and infections can affect blood flow and therefore cause swelling of the turbinates. Since the turbinates are at the very front of the nasal opening, they are very susceptible to allergy and dust irritation.
When the turbinates become enlarged, they block breathing and make you feel congested. The inferior turbinates are often the source of breathing problems. When the inferior turbinates become enlarged it is referred to as inferior turbinate hypertrophy.