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You might be surprised by this, but in fact, when you exhale, one nostril always has a significantly stronger airflow than the other. This is a completely normal biological process called the nasal cycle.

Have you ever tried placing your hand under your nose and noticed that the airflow from one nostril is much stronger than the other? - Image: AI

Don't worry that you have a cold or a deviated septum. In reality, our bodies are performing a completely normal biological process called the nasal cycle.

Several times a day, the two nostrils automatically alternate their "dominant" role to ensure optimal respiratory function.

In an article on The Conversation, Dr. Adam Taylor from Lancaster University (UK) explains that on average, about every two hours, when we are awake, the hypothalamus in the brain silently controls this switching.

When one nostril is clear and allows airflow, the other enters a temporary "congestion" phase. This process occurs less frequently during sleep due to slower breathing, but it is key to protecting the body's "first line of defense."

The most important reason for this cycle is to prevent dryness and damage to the mucous membrane. With approximately 12,000 liters of air passing through the nose each day, one nostril constantly working would become fatigued, dry, and more susceptible to pathogens.

The "congestion" phase is actually when the body increases blood flow to the blood vessels in the nose, helping to moisturize, warm, and repair the mucous membrane tissues.

Interestingly, studies have also shown a connection between the dominant nostril and mental state. When the right nostril is dominant, the body is often in a more alert or stressed state.

Conversely, when the left nostril takes the primary role, we tend to be more relaxed and calm. Especially in right-handed individuals, the left nostril tends to be dominant most of the time.

However, many factors can disrupt this natural cycle. Most commonly, respiratory illnesses like colds, flu, or seasonal allergies cause tissue inflammation and increased mucus production.

Overuse of decongestants for more than 5 days can also backfire, causing "medicinal rhinitis" and sudden swelling of the tissues. Additionally, structural issues such as a deviated septum or nasal polyps can cause one nostril to feel constantly congested, affecting sleep quality and breathing.

Even your sleeping position affects your breathing. Gravity causes blood and sinus fluid to pool towards the nostril closest to your pillow, which is why you often feel congestion in one nostril when lying on your side.

Typically, nasal congestion from a cold will clear up on its own after about two weeks. However, if you notice persistent nasal congestion on one side lasting longer than 14 days, accompanied by unusual mucus, it's time to seek medical advice to ensure your respiratory system remains in optimal condition.