The other day I tried to meditate. I put my headphones on, opened the meditation app, pressed play, and began to listen to the soothing voice:
“Welcome to this guided meditation. Make yourself comfortable. Keep an upright posture and relax.”
I configured my facial muscles into a relaxed smile and sighed: “Ahh…”
“Now close your eyes and take a deep breath in through your nose,” the voice continued. I complied and took a deep breath in — through my left nostril?! “Huh?” I thought, “That’s weird. Why is all the air just coming through one side of my nose?”
“Exhale…” the voice continued.
“Seriously, what’s up with my nose?”
“Inhale…”
“Helloooooooooo? Right nostril?” I tapped on it, but with no effect.
“Exhale…”
“Jeez…. How am I supposed to meditate if only half my nose is working?!”
At first I wondered whether it’s just me. Could I still have that crayon stuck in my nose from back when I was a toddler? But no, that can’t be it. My two nostrils are taking turns. Surely there isn’t a crayon shifting from the left to the right side of my nose and back every few hours. There must be another explanation.
So I decided to look it up, to find out why there is always one nostril enthusiastically sucking in air while the other is doing a half-assed job. What I discovered is the nasal cycle.
The nasal cycle is the often unnoticed alternating partial congestion and decongestion of the nasal cavities in humans and other animals. […] It should not be confused with pathological nasal congestion.
Interesting… So it’s normal for only one nostril to suck in all the air and for the other to only let a trickle through. And it’s also normal for the two nostrils to take turns.
After further investigation I found out that apparently one nostril gets sort of an erection, swells up, and restricts how much air gets through, while the other, which was swollen before, deflates, opens up widely, and allows air to rush in.
But why? Why won’t both nostrils just do a proper job at breathing and suck in as much air as possible?
Well, it turns out that there are two main reasons for this:
It gives one side of your nose a break, andit helps you smell better.
Now, the reason why a nostril needs a break has nothing to do with having inhaled too many stinky particles, as I first thought. It’s not that after sitting too long on the toilet the nostril that’s on breathing duty goes “Oh God, pooh… Okay, that’s enough! Your turn, pal,” and then the other nostril takes over. The cycle happens all the time, regardless of what you’re smelling.
No, the reason a nostril needs a break is that it otherwise dries out. Your lungs require air that’s both moist and warm. So one of the main functions of your nose is to warm up and humidify all the incoming air and to do that properly your nostrils need to maintain a tropical climate.
- But without a break from the onslaught of the incoming air, a nostril can only maintain that climate for so long before drying out and developing painful cracks. Thus, before that happens, your autonomic nervous system (which is the autopilot part of your nervous system) orders your other nostril to take over for a while.
Now what about the other reason? Why does the nasal cycle help you smell better?
Well, it turns out that smell is detected by chemoreceptors in your nose. For instance, you can smell a wet poodle because it emits smelly particles called odorants. These odorants then float through the air and when you breathe them in, they form temporary chemical bonds with the chemoreceptors in your nose. These chemical bonds, in turn, stimulate your chemoreceptors to send an electrical signal to your brain and — ta-dah! — you end up smelling the poodle.
Now, the thing is that the odorants need to hang around your nose’s receptors for a little while to bind with them. However, not all odorants are equally likely to bind. Some of them bind more easily than others. We can think of it as some of them being stickier than others.
Those odorants that are particularly sticky need to whoosh in speedily to not get stuck at the entrance of your nose and to reach the receptors that are further in. The less sticky ones, in contrast, need to enter the nose at a more leisurely pace so that they have a chance to bind to your smell receptors without just zipping by due to too much airflow.
So what your nose does is restrict the air in one nostril to slow down the non-sticky odorants while vigorously sucking in air through the other nostril to ensure that the sticky ones get deep into the nose. That way you can smell both the sticky and the non-sticky odorants of whatever you’re holding under your nose:
Wrapping up
Your nostrils split their workload. They alternate congestion and decongestion in a process called the nasal cycle. At any one time, one nostril is the dominant one through which most of the air is inhaled, while the other takes it a little easier and restricts the airflow. After a few hours, the two nostrils exchange their roles and the one that used to suck in most of the air now restricts it while the other is now wide open.
The alternating successive congestion and decongestion of your nostrils ensure that neither one of them dries out. Moreover, by always having one nostril with reduced airflow and one with increased airflow, you are able to distinguish between a wider range of smells, which would not be possible if you were inhaling in equal measure through both sides of your nose. Now whether that’s a good thing depends on where you are. I certainly wouldn’t mind NOT being able to distinguish the nuances of a men’s locker room.
