That's not actually true. If you research it, you'll find that most people's nostrils alternately dilate and contract (the tissues reduce/swell). Most of us breathe primarily through only one nostril at a time, and it switches approximately every half hour. This is entirely unconscious and we're generally not aware of it.
There is a little bit of airflow in the constricted nostril, but nowhere near comparable to the other. You can test this by covering up your nostrils individually and comparing how easy it is to breathe through them. Then wait a half hour and try it again. (Note that a minority of people do not have this.)
However, this is not something you can consciously control or override, any more than you can override contractions in your intestine.
Came here to say the same. I was completely unaware of the nasal cycle until I got further into my meditation practice, but you totally can notice which nostril is taking in more air if you practice training your awareness on it. It was surprising to me when I first noticed it.
One of my yoga teachers has us find the one that is currently dominant in the cycle before we practice nadi shodhana pranayama, and then select the starting nostril based on that.
> This is entirely unconscious and we're generally not aware of it.
I wonder if I'm unusual in that I can consciously control which nostril is open or closed. Most of the time the switching from side to side is unconscious but if I concentrate, I can cause it to happen consciously. This is really useful when I have a cold and a blocked nostril and I want to get some relief when blowing my nose doesn't help - I just focus on allowing that side of my sinuses to open and after a few minutes it will happen.
It’s more like one nostril is high-velocity and the other is low-velocity, not that one is completely blocked. The evolutionary reason is thought to be that it aids the perception of low PPM volatile organic compounds (i.e. bad smells = rot, toxic chemicals) because the ‘blocked’ nostril is used as a sense chamber which lets the air spend more time within, thus increase the effective sensitivity of your sense of smell.
If you do not have this behaviour (which can disappear with certain neurological diseases or just idiopathically not exist) you also likely have a reduced sense of smell.
Can confirm that I "smell" through one nostril at a time. I can smell more sensitively than others (for example, realise that milk is rotten before others do). I have noticed that when I try blocking one of my nostrils, my sense of smell is considerably lower, and it is not always the left nostril or always the right nostril. It kind of alternates, and I don't know the pattern. It might be that both nostrils alternate doing the task of smelling at different times.
Yep, one of my nostrils always feels blocked but my fiancée’s nostrils are always wide open on both sides. I’m practically green with envy. Only being able to breathe using half of your nose is frustrating.
There is a little bit of airflow in the constricted nostril, but nowhere near comparable to the other. You can test this by covering up your nostrils individually and comparing how easy it is to breathe through them. Then wait a half hour and try it again. (Note that a minority of people do not have this.)
However, this is not something you can consciously control or override, any more than you can override contractions in your intestine.