I believe you must have experienced the situation where one nose is blocked and the other is normal when sleeping at night.

But why is it that when the nose is blocked, one nostril is usually open but the other is blocked?

This is because one of the two nostrils is originally connected and the other is not.

In fact, not only when you have a cold, usually one of your noses is more open and the other is less open. The two nostrils are always taking on the workload alternately.

Each nostril has its own working and working time, and their working times are staggered. This is called the nasal cycle. When you go to work, your nostrils are ventilated; when you go off work, your nostrils become congested and become somewhat blocked.

If you feel your breathing carefully, you will find that whenever you inhale, one nostril always inhales much more than the other.

The team leader of the nostrils is the autonomic nervous system - because its name is very long, let’s call it Shensong for now. God is responsible for managing your breathing, heartbeat, digestion, etc., which does not require the intervention of the monitor-brain. So, what exactly happens to the nostrils when you have a cold and stuffy nose?

When you have a cold, your nose will secrete a lot of mucus. That’s right, your snot. It's the mucus that makes the resting nostril feel blocked, especially when you sleep on your side.

So, why do the nostrils work alternately?

One reason is that alternating nostrils can distinguish odors more effectively. In our noses, what determine smells are odor receptors, which are little laboratories that analyze smells. Some odor receptors are good at picking up odors in fast airflow, while others are better at picking up odors in slower airflow. There is a tissue inside the nostrils that swells when filled with blood. They are like gates to the nostrils, controlling the ventilation and blockage of the nostrils.

Whenever the nostrils change shifts, one nostril will close its door and go home to sleep, and the passage of this nostril is narrowed; the other nostril will consciously open its door and start working. --breathe.