How SIGHING keeps us alive: Deep breathing prevents the lungs from failing (which is why the average person does it 12 times an hour)

  • Study: Average person racks up 12 sighs an hour - 1 every 5 minutes
  • Experts found sighs are triggered by two sets of chemicals in the brain 
  • Sighing keeps us alive by popping tiny alveoli in the lungs open when they collapse, preventing the lungs from failing over time

By Fiona Macrae, Science Editor For The Daily Mail

Published: 11:02 EST, 8 February 2016 | Updated: 19:12 EST, 8 February 2016

To generations of movie goers, a sigh is just a sigh.

But despite the words sung by piano player Sam in Casablanca - 'a kiss is just a kiss, a sigh is just a sigh', in the famous song As Time Goes By - there's more to a sigh than meets the eye.

In fact, scientists say sighing helps keep us alive.

Indeed it is so vital that the average person racks up 12 sighs an hour – that’s one every five minutes.

Scientists have discovered the mechanism behind how we sigh - and say it's vital for keeping us alive

Scientists have discovered the mechanism behind how we sigh - and say it's vital for keeping us alive

The revelations come from US neuroscientists who discovered how the brain turns normal breaths into sighs.

In experiments on mice, they pinpointed two small clusters of brain cells.

One set of cells produces two chemicals which ‘talk’ to the second set.

These then stimulate the breathing muscles, triggering a sigh rather than a normal breath.

Mice normally sigh 40 times an hour, the journal Nature reports.

However, when one of the brain chemicals, or neuropeptides, is blocked, the rate is halved. And when both of the compounds are blocked, they simply cannot sigh.

The find, from Stanford University and the University of California, Los Angeles, could shed light on other quirks of breathing.

Researcher Mark Krasnow said: ‘Unlike a pacemaker that regulates only how fast we breathe, the brain's breathing centre also controls the type of breath we take.

‘It's made up of small numbers of different kinds of neurons.

Two tiny clusters of brain cells that are responsible for transforming normal breaths into sighs (pictured in fluorescent green) have been discovered - and could shed light on other quirks of breathing

Two tiny clusters of brain cells that are responsible for transforming normal breaths into sighs (pictured in fluorescent green) have been discovered - and could shed light on other quirks of breathing

'A kiss is just a kiss, a sigh is just a sigh', sings piano player Sam (played by actor Dooley Wilson, pictured) in the 1942 film Casablanca. But scientists have discovered there is more to sighing than meets the eye

'A kiss is just a kiss, a sigh is just a sigh', sings piano player Sam (played by actor Dooley Wilson, pictured) in the 1942 film Casablanca. But scientists have discovered there is more to sighing than meets the eye

‘Each functions like a button that turns on a different type of breath. One button programs regular breaths, another sighs, and the others could be for yawns, sniffs, coughs and maybe even laughs and cries.’

The discovery could also lead to new treatments for people with anxiety disorders and other conditions which mean their lives are plagued by uncontrollable sighing.

But, as annoying as sighing may be for those who overhear it, the process is vital to life.

The oxygen in the air we breathe enters our bloodstream from tiny sacs deep within the lungs called alveoli.

Sometimes these collapse and sighing pops them back open, stopping the lungs from failing over time.

While the study tells us how we sigh, it doesn’t explain why we do it more when we are sad or disappointed or frustrated.

Researcher Jack Feldman said: ‘It may be that neurons in the brain areas that process emotion are triggering the sigh neuropeptides – but we don’t know that.’ 

Oxygen enters our bloodstream from tiny sacs deep within the lungs called alveoli (pictured). Sometimes these collapse and sighing pops them back open, stopping the lungs from failing over time, scientists found

Oxygen enters our bloodstream from tiny sacs deep within the lungs called alveoli (pictured). Sometimes these collapse and sighing pops them back open, stopping the lungs from failing over time, scientists found

Comments (17)

Share what you think

 View all

The comments below have not been moderated.

 View all

The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.

Add your comment

By posting your comment you agree to our house rules.

Who is this week's top commenter? Find out now