The Nasal Cycle: An In-Built Breathing Balance

You may not have noticed, but when you breathe in and out through your nose, the airflow in your nostrils isn’t equal. The difference, which is subtle, is due to the phenomenon called the nasal cycle. This cycle is a physiological rhythm controlled by the hypothalamus—a small, almond-shaped structure at the base of the brain that controls many of our automated functions.

Nasal cycles last from 90 minutes to four hours. During each cycle, one nostril is more dominant while the other is more congested. This congestion is not an illness and is not caused by a cold or allergies. Rather, in a normal healthy process, erectile tissue that lines the nasal cavity swells or shrinks due to changes in blood flow. On the side where the tissue is swollen, airflow is more restricted. On the other side, the air flows more freely.

So why does this happen?

There is little research on why we have this cycle, but there are theories that are arguably plausible.

One group of theories is called “functional purpose theories”. For example, the olfaction enhancement theory states that varied airflow helps to detect a wider range of scents. Another is that it improves thermal regulation and helps prevent the drying effects of a constant flow through one nostril.

Another theory is that nasal breathing has neurocognitive effects, i.e., it affects how our brain works. Some small studies have shown that breathing through the right nostril increases activity in the left brain, and breathing through the left nostril activates the right hemisphere. While there is little research in this space, yogic breathing practices like nadi shodhana have long been touted as providing these benefits.

Some have framed the nasal cycle as an automated biohack—a built-in way the breath can influence our biology. One claim is that breathing more through your left nostril lowers your blood pressure. This idea is based on yogic traditions of alternate nostril breathing but has little scientific backing. We know breathing can affect our nervous system, and maybe that is what is happening during the cycle.

Where does that leave us?

While there may be limited scientific research into these theories, they may be correct, and it may be possible to take advantage of them. Yogic breathing has been shown to have health benefits (e.g., Bhramari breath—special humming—increasing nitric oxide production in the nasal cavity, which can help improve oxygen uptake). Ancient yogis may not have understood the science of “why” breathing practices are beneficial, but they did understand it made them feel better and helped to control their mood. Future research may provide more support for some of these theories. Unfortunately, that may be some way off as there is little commercial incentive to research breathing techniques.

None of that should stop you from experimenting with your breath. If breathing through your left nostril makes you more relaxed, then be guided by how you feel. Don’t wait for science to catch up to what works for you!

Disclaimer

This blog is for informational purposes only. It is not medical advice. Always consult a healthcare professional for personalized guidance and treatment.