There are plenty of health claims about humming. They include reducing stress, helping you breathe more easily, relieving sinus congestion, lowering your blood pressure and lifting your mood.

That's a lot of potential benefits for something that comes pretty naturally to most of us.

Can something so simple really be healthy? Here's what we know so far.

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Humming's all around us

Humming is likely connected to our earliest memories of comfort and care, as caregivers soothe infants with lullabies and humming. Infants, unable to comprehend speech, take in the melodic information, making humming one of our earliest forms of bonding through sound.

As we get older, we hum when we're happy, embarrassed, displeased or in agreement with someone. Mmm. Hmm.

We often hum tunes unconsciously, even ones we don't like, by mirroring what we hear. Some tunes can even get stuck in our heads if they contain hooks and repetition. And let's face it, humming's also handy when we can't remember the words.

Then there are songs that feature humming, such as Enya's The Humming, the 90s smash hit Mmm Mmm Mmm Mmm by the Crash Test Dummies, or James Blake's Retrograde.

What happens when we hum?

When we hum, we create a buzzing sound with our mouth closed. We force air through our vocal folds (the newer term for vocal cords), causing them to vibrate and produce sound. We can control the pitch by adjusting the tension of our vocal folds to hum a tune.

All this vibration likely stimulates our vagus nerve (we actually have two), part of our parasympathetic nervous system. This is the nervous system that calms and restores body functions such as our heart rate, digestion and respiration.

People often hum as a way to relax. Their heart rate can decrease and their heart rate variability can increase. Heart rate variability refers to the slight fluctuation in time between each heartbeat. A higher heart rate variability is associated with better health.

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When we hum, oscillating sound waves may also affect the sinuses, leading to increased levels of nitric oxide in the nose. One study found a 15-fold increase of nasal nitric oxide from humming compared to exhaling quietly. Nitric oxide is involved in everything from brain and immune function to blood flow to the lungs and sexual arousal.

In another study, researchers looked at people with allergic rhinitis (such as people with pollen or dust allergies). When they hummed, they had higher levels of nasal nitric oxide and had fewer sinus problems compared to those who exhaled silently.

Humming also leads to some unexpected psychological effects. These include increased body awareness and "decentering" - the ability to separate oneself from thoughts, emotions and sensations.

How about chanting?

Humming also plays an important role in chanting. One example is in the ancient meditation technique bhramari pranayama (which can involve humming while gently closing the ears with your fingertips).

It is no coincidence one of the world's most chanted sounds - om - involves a long, sustained hum at the end. Chanting all sorts of various sounds and prayers is believed to connect practitioners to the spiritual realm and induce feelings of peace.

Chanting has cognitive benefits, such as mindfulness, and altered states of consciousness, such as flow - a feeling of being absorbed by and deeply focused on an activity. Chanting also reduces stress.

In a nutshell

We hum for lots of different reasons, suggesting that these common vocalisations play an important role in our lives.

Is humming healthy? More research is needed. But humming feels good, improves our mood, distracts us from boring tasks, and can even be used for spiritual practice. Happy humming!

Authors: Gemma Perry - Post doctoral researcher, Bond University | William Forde Thompson - Professor, Faculty of Society & Design, Bond University