Image copyright Getty Images Image caption Andien posted photos of herself, her husband and her young son with tape over their mouths

"It's funny if you think about it. We learn about a lot of things that we don't do, but we don't learn about something that we do all the time: breathe."

Andien, a popular Indonesian singer, shocked her fans when she posted a lengthy Instagram story about breathing - along with photos of herself, her husband and their two-year-old son with tape over their mouths.

She revealed that her family had been practising something called Buteyko for the past three months. It involves finding ways of breathing through your nose - one of which is taping your mouth closed while you sleep.

Buteyko, Andien claimed, had helped her sleep better, had stopped her from getting dry throat, and had rid her of bad breath.

But does mouth-taping work and, more importantly, is it safe?

What is 'Buteyko'?

The Buteyko technique was first developed in the 1950s by the Soviet doctor of the same name, Konstantin Pavlovich Buteyko.

He believed that respiratory conditions, asthma in particular, could be linked to the way people breathed. He believed that if patients were taught to breathe correctly, through their noses, their lung problems would go away.

Almost seven decades later and the alternative therapy remains popular, with Buteyko practitioners around the world now hailing the benefits of breathing exercises and taping the mouth shut to sleep.

Buteyko has been claimed to improve a host of ailments, from diabetes to chronic fatigue, ADHD and depression. But perhaps the condition it has become most closely associated with is sleep apnoea.

Sleep apnoea is when someone's airway is blocked or restricted while they sleep, which means they are unable to breathe as easily. As a result they get low quality sleep, which can lead to tiredness, depression, and other illnesses.

This is also why sufferers snore - that unpleasant sound is the air struggling to get in and out of someone's trachea.

Patrick McKeown, founder of the International Buteyko Clinic, told the BBC that "mouth-breathing is a big contributing factor to obstructive sleep apnoea (OSA)" because it can push the tongue back and obstruct the airway. Taping the mouth closed, he claims, can prevent this from happening.

'You don't just close your mouth'

But doctors disagree, and say that this is a simplistic understanding of the condition.

"I understand why it's preferential to breathe through your nose, but most people don't open their mouth unless they're having trouble breathing through their nose," Dr Kathleen Yaremchuk, a senior ENT surgeon and sleep specialist in Detroit, told the BBC.

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Someone suffering from OSA, she adds, cannot stop the condition "just by closing your mouth".

"Oral appliances you use [for OSA] bring your jaw forward when you wear them, so that helps with sleep apnoea - but it's not just closing the mouth, it's bringing the mandible forward to open the airway."

Professor Nirmal Kumar, an otolaryngologist and president of the British medical organisation ENT UK, agrees, and told the BBC that there was "no convincing body of evidence in the medical literature to support this treatment [Buteyko]".

Image copyright Getty Images Image caption Mandibular advancement braces, which are used to treat sleep apnoea, 'don't just close the mouth'

He adds that doing any breathing exercises - Buteyko or not - can generally improve asthma and other respiratory symptoms, which may be why people believe that it's helping. But breathing exercises are "part of our standard advice and treatment [as doctors] anyway".

What are the risks?

Aside from the fact that it's barely effective, both doctors warn that taping your mouth - or your child's mouth - could be dangerous.

"If you were to get sick and you had to vomit, you wouldn't be able to," Dr Yaremchuk warns. In the worst case scenario this could cause someone to choke.

When it comes to young children, Mr McKeown explicitly warns against taping their mouths. He said he had seen Andien's Instagram photo of her toddler, and that it's "not at all recommended" by Buteyko practitioners.

"For young children, the earliest we would [tape] is maybe five years of age, but we don't put the tape directly over the lips."

Prof Kumar adds that children can also have greater difficulty breathing through their nose, as well frequently being sick.

Image copyright Getty Images Image caption File photo: toddlers and babies often sleep with their mouths open because their noses are more likely to be blocked

He says that Andien taping her two-year-old child's mouth is "the last thing we would advise anybody, because there is a significant danger of cot death".

While in an emergency most adults are likely to wake themselves up and rip the tape off, children cannot, he adds.

"There are problems in children's nasal passages that can cause blockages," such as adenoids or a simple blocked nose. In these cases, "they have to breathe through their mouth, or they'll die".

If you are snoring or are having other problems breathing, both doctors recommend seeing a medical professional for treatment.