Why don't we hum while running from danger?

Have you noticed that people rarely hum when they're overwhelmed?

We hum while cooking, gardening, folding laundry, walking the dog, or rocking a baby to sleep. These are usually moments that don't require constant vigilance. The body has a little more space to breathe, and somehow a tune appears almost without us noticing.

You've probably heard that humming stimulates the vagus nerve, increases nitric oxide production and helps regulate the nervous system [1-3]. Research does support many of these physiological effects, and they're certainly worth talking about.

But before asking what humming does, I think there's a more interesting question.

What information does humming give the brain? Most of us think of humming as something we do when we're already relaxed. Yet humming changes several things in the body at the same time, and the brain is constantly paying attention to those changes.

Every second, it combines information from our breathing, heart rate, muscles, posture, movement, facial expressions and countless other sensory signals to estimate what's happening both inside and outside the body. Based on that ongoing stream of information, it decides how much energy, attention and protection we need in that moment.

I like to think of the brain as a detective. It never experiences the world directly. Instead, it's constantly piecing together clues. One clue on its own doesn't tell the whole story, but when enough clues begin pointing in the same direction, the brain updates its best guess about what's happening.

Humming changes several of those clues all at once.

Your breathing naturally becomes slower and your exhalation lasts longer. Your vocal folds, throat, chest and face begin to vibrate. Your attention shifts from whatever is happening around you to the sensation of the sound moving through your body.

Rather than flipping a single "calm switch", humming changes the overall pattern of information reaching the brain.

1. It changes the way you breathe

Unlike speaking, humming almost always happens during a slow, steady exhalation.

Breathing is one of the many signals the brain uses to estimate the body's current state. When the exhalation becomes longer, it is often accompanied by greater parasympathetic influence, changes in heart rate variability and a gradual shift away from physiological urgency. [4]

It's not that the brain notices a long exhalation and immediately decides WE ARE SAFE. Instead, breathing becomes one more piece of evidence that contributes to the bigger picture.

2. It gives the brain more sensory information

Humming isn't just something you hear but also something you feel. The vibration travels through your vocal folds, throat, jaw, chest and face, stimulating specialised sensory receptors called mechanoreceptors. These receptors continuously send information back to the brain.

We often think of regulation as something that starts with our thoughts. But the conversation is happening in both directions. The body is constantly sending updates, and the brain is constantly integrating them.

Humming simply changes the quality of those updates.

3. It increases nitric oxide

One of the most fascinating discoveries about humming has nothing to do with stress.

Studies have shown that humming dramatically increases the amount of nitric oxide in the nasal passages compared with quiet breathing.[1–3]

Nitric oxide helps regulate blood flow, supports healthy sinus function and has antimicrobial properties.[1–3,5] While this doesn't explain why humming feels calming, it's a beautiful reminder that one simple behaviour can influence several physiological systems at the same time.

4. It brings your attention back into your body

Many of us spend the day focused on everything except ourselves.

• Emails

• Deadlines

• Meetings

• Children

• Notifications

• Responsibilities

Humming naturally interrupts that outward focus.

As you notice the vibration in your chest, throat or face, your attention moves towards sensations inside your own body. Neuroscientists call this interoception: our ability to notice and interpret internal bodily signals.

The stronger our interoceptive awareness, the easier it becomes to recognise stress before it builds into something much bigger.

So is it really about the vagus nerve?

The vagus nerve is certainly part of the story. Some of its branches are involved in vocalisation, and researchers continue to investigate how breathing, vocal sounds and autonomic regulation influence one another. But reducing humming to "a vagus nerve exercise" misses how beautifully interconnected the nervous system really is.

Humming changes the way we breathe.

It changes the sensory information coming from the body.

It changes where our attention rests.

It even changes the chemistry inside the nasal cavity.

The brain doesn't rely on a single signal to understand what's happening. It integrates many signals at once and looks for patterns. That's why I find humming so fascinating - because it reminds us how the brain learns (and not because it's another instagram hack).

Every experience gives the brain more information:

• A walk in nature

• A conversation

• A hug

• Gentle movement

• Music

• Laughter

• Rest

• Humming
  

None of these changes us overnight. But each one adds another piece of evidence about the world around us and the state of the body we're living in. Over time, those experiences shape the brain's predictions, and those predictions influence how the nervous system responds.

To me, that's the real value of humming. It's not a magic technique. It's one small, beautifully human way of changing the conversation between the body and the brain.

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References

[1] Weitzberg E, Lundberg JON. Humming greatly increases nasal nitric oxide. American Journal of Respiratory and Critical Care Medicine. 2002. https://pubmed.ncbi.nlm.nih.gov/12119224/ 

[2] Maniscalco M, Weitzberg E, Sundberg J, Sofia M, Lundberg JON. Assessment of nasal and sinus nitric oxide output using single-breath humming exhalations. European Respiratory Journal. 2003. https://pubmed.ncbi.nlm.nih.gov/12952268/ 

[3] Maniscalco M, Sofia M, Weitzberg E, Carratù L, Lundberg JON. Nasal nitric oxide measurements before and after repeated humming manoeuvres. European Journal of Clinical Investigation. 2003. https://pubmed.ncbi.nlm.nih.gov/14636292/ 

[4] Paulus MP, Khalsa SS. Neural mechanisms of respiratory interoception. Autonomic Neuroscience. 2024. https://www.sciencedirect.com/science/article/pii/S1566070224000353 

[5] Törnberg DCF, Marteus H, Schedin U, Alving K, Lundberg JON, Weitzberg E. Nasal and oral contribution to inhaled and exhaled nitric oxide: a study in tracheotomized patients. European Respiratory Journal. 2002. https://pubmed.ncbi.nlm.nih.gov/12030725/  The references listed are selected to help curious readers explore the science behind this topic. This article is intended for educational purposes and should not replace personalised medical advice.