Even at rest you're always taking sides, as when you breathe (provided you don’t have a cold) you’re constantly switching your “dominant nostril” – that is, the nose hole you’re breathing from the most. You might not notice it happening, but your nostrils are constantly taking turns in the lead role, and the side that’s in charge can actually correlate to activity in the brain.
Known as the nasal cycle, the process is an unconscious action that sees the partial congestion and decongestion of the left and right sides of your snoot. The magic happens at what’s known as the “nasal conchae”, a long and narrow shelf of bone that’s found in both nostrils. The cycle can put your nose at a ratio of 3:1 in terms of airflow, according to a report from Live Science.
So, what’s the point? There are a few theories, most of which center around moisture, pathogen clearance, and general nose maintenance.
Our nostrils are filled with tiny hairs and gooey mucus. These help to keep us healthy by trapping undesirables from the air before they can migrate to our respiratory system and make us sick. By switching from left to right, it’s possible that the nasal cycle reduces airflow on one side just long enough to keep it nice and moist before it picks up the slack once more while the other side gets a rest. This may also help our immunity in giving our bodies time to ditch whatever's been snagged in the resting nostril so that the traps are clear and ready to go.
When not disrupted by illness or lifestyle (there’s more than air that ventures into some people’s nostrils – even teeth), the cycle is thought to switch it up roughly every two hours and continues even when we’re asleep. The downside to switching the dominant nostril is that if something has gone awry on one side, you might find that nasal breathing becomes less comfortable.
For example, if you're getting over the last dregs of a cold and only your left nostril remains inflamed, you’d likely be happy as a clam while your right nostril is dominant. However, if it switched while you were asleep, you might wake up as your left nostril isn’t able to fulfill its part of the bargain.
Interestingly, early studies found that nostril dominance sometimes correlated to brain activity. Using an electroencephalogram, researchers observed that the leading nostril was linked to increased activity in the opposite side of the brain – so when the left nostril was the most active, so too was the right side of the brain.
Since then, a battery of research has been conducted into the effects of both the naturally dominant nostril and forced nostril dominance (manually plugging one half of your nose) on brain activity. Some have run with this idea to see if forced nostril breathing can bring on a more productive mental state, as is seen in yoga practices tied to the physiological phenomenon. Studies have looked into its effect on brain activity and performance in cognitive tasks and found that it can influence both parameters.
So, who’s doing the lion’s share on your face right now?