Your nostrils take turns breathing throughout the day.

German doctor Richard Kayser first described this process in 1895. Inside your nose, there are small structures called turbinates. These structures are made of bone and tissue that can swell with blood. When the tissue in one nostril swells, it narrows the airway and makes air move slower on that side.This cycle helps keep your nose healthy. Constant air movement can dry out the inside of your nose. By slowing down the air in one nostril, the body gives the lining time to stay moist and recover. This moisture helps the nose filter out dust and germs before they reach your lungs.The nasal cycle also helps you smell better. Some scents are easier to pick up when air moves quickly. Other scents need more time to be absorbed by your smell receptors. Having one fast stream of air and one slow stream allows your brain to detect a wider variety of odors.About 80% of healthy adults have this cycle. Most people do not notice it unless they have a cold or a blocked nose. Scientists use a tool called a rhinomanometer to measure this airflow. Even though the nostrils switch roles, the total amount of air entering your body stays the same.