One of Your Nostrils is Always Working Harder Than the Other

People breathe primarily out of one nostril at a time.

The human nose is a biological wonder. 

It can smell up to 1 trillion odors, trap harmful debris in the air before it enters your lungs, and affect your sex life. 

But arguably its most important job is to condition the air you breathe before that air enters your respiratory tract. 

This means warming and humidifying the air before it passes to your throat and beyond. To do this, the nose undergoes a nasal cycle in which one nostril sucks in the majority of the air while the other nostril takes in the remaining portion. 

A few hours later (on average), the nostrils switch roles. This cycle is regulated by the body’s autonomic nervous system, which swells or deflates erectile tissue found in the nose. 

Although we don’t notice this switch throughout the day, if you cover your nostrils with your thumb one at a time, you’ll likely observe that air flow through one is significantly higher than in the other. 

This is also why one nostril tends to be more congested than the other when you have a cold (the nondominant one gets more filled with mucus).

There are a few possible reasons for this nasal back-and-forth. Some scientists theorize that the cycle actually improves our sense of smell. 

Because scent molecules degrade at differing rates, some smells are easier to identify through fast-moving air (in the dominant nostril), while others are more easily picked out in slower currents of the nondominant, usually more congested, nostril. 

Very few smells can get past our nose undetected thanks to this alternating nasal superpower.