Health News

It can stop you breathing more than 100 times an hour. What’s sleep apnoea?

Sometimes the silence can be more alarming than the snoring – as the bed partners of people with apnoea will know. Why are sleepers left gasping for breath, and how does everyone get a good night’s rest?

Save articles for later

Add articles to your saved list and come back to them any time.

Each night was like a wrestling match with her own airways. With the lights out, her children asleep and the house quiet, Melinda Mahlberg would begin to snore. Her husband, Troy, wore earplugs. He could still hear her. Her breathing sounded laboured as the snoring continued all night; the pair never started a day fully rested.

Melinda was exhausted. Tests to find the cause of her fatigue had found nothing wrong. She wasn’t just tired from being a mother of three and a receptionist with a busy social life; there was something else amiss. “I’m too young to be this tired,” recalls the 45-year-old. “Around my eyes was tense. And my brain was all foggy.”

Eventually, Melinda spent a night away from home – hooked up to monitors and breathing equipment at a clinic. They showed that, during at least some of her sleep, she stopped breathing, for seconds at a time, once every minute. “It was a bit of a shock.”

Sleep apnoea affects about 5 per cent of Australians; they will wake most days with the fuzziness of what Melinda calls a “tired hangover”. Fatigue can be dangerous, especially for drivers or people working with machinery. In the longer term, apnoea increases the risk of heart disease, high blood pressure and possibly even dementia.

So what causes sleep apnoea? Who gets it? And how does someone with it (and their bed partner) get a good night’s sleep?

Melinda Mahlberg was unsure why she felt so tired until a test revealed she has sleep apnoea. Credit: Edwina Pickles. Artwork Aresna Villanueva

What’s sleep apnoea?

The snores of Kare Walkert, a Swede with sleep apnoea, reached a Guinness world record of 93 decibels in the 1990s, about the equivalent of a lawn mower. A British woman’s snoring has since reportedly exceeded 111 decibels (as loud as someone shouting into another person’s ear). Fortunately, most snoring volumes are usually around the level of a quiet conversation. About half of Australian adults snore, including most people with sleep apnoea.

But something extra happens with apnoea: a sleeper stops breathing for 10 seconds or more at least five times an hour. The word itself comes from the Greek for “without breath”. Cases range in severity. At one extreme, a woman with apnoea who also had a condition of the nervous system stopped breathing for 233 seconds in a hospital in the United States.

Starved of air, people with apnoea wake. “I would have more minor [episodes] where you don’t realise you’re waking up,” says public servant Susan Graham, a Melburnian who has managed her sleep apnoea for 15 years. “Then you have really extreme ones where it sort of builds up and you jerk yourself awake.”

Air travelling into our windpipes passes the base of the tongue, the tonsils, an area of muscular tube called the pharynx, and the voicebox, where vocal cords vibrate to produce sound. The muscles throughout this area, known as the upper airway, tend to relax as we sleep. If they become too floppy, our breathing can cause them to vibrate, causing snoring. But in some people, the muscles relax so much the usually moist inner surfaces of the sides of the pharynx can stick together blocking off the airway. “It’s a bit like having a wet piece of paper against a glass window,” says Associate Professor Megan Rees, head of respiratory and sleep disorders at the Royal Melbourne Hospital.

If the blockage is partial – a condition called hypopnea – it can cause slow and shallow breathing. Obstructive sleep apnoea is when the airway closes until the person’s breathing response kicks in – the break point where it’s believed our neurological and mechanical systems take over to make us gasp for air.

Anatomy is one cause: people with smaller pharynxes are more susceptible to apnoea. Others have an overbite that can crowd the soft tissue at the back of the airway. “I come from a family of bad snorers,” says Graham. “I think it’s sort of in the family genes to have quite a narrow airway.” In fact, if an immediate family member has sleep apnoea it doubles a person’s chance of having it.

When physicians first described sleep apnoea in the 1960s, they linked it to obesity. A patient had Pickwickian syndrome (obesity hypoventilation syndrome), a breathing condition named after a corpulent carriage driver in Charles Dickens’ The Pickwick Papers who would fall asleep running errands. The patient slept just a few hours because of a “cyclic repetition of arousal and slumber”.

Today, 58 per cent of people with moderate to severe sleep apnoea are believed to be obese. Fat in the tongue and neck can cause the airway to collapse.

Sleep apnoea is about three times more common in men than women. Some of this could be due to under-diagnosis in women but also to how body weight is distributed. “If you’re carrying excess body weight in a central area and around your neck, you’ll be more at risk of sleep apnoea. Whereas women who are overweight often carry that extra weight below their waist,” Rees says.

‘They start to snore a bit in their 30s and then snore loudly in their 40s and have sleep apnoea in their 50s.’

Still, in both women and men, age tends to make apnoea worse. “Everything gets saggier, so the muscular tube in the back of the airway just gets floppier,” says David Cunnington, clinical chair of the Australasian Sleep Association. “They start to snore a bit in their 30s and then snore loudly in their 40s and have sleep apnoea in their 50s.”

In fewer than 1 per cent of cases, people have no airway blockage, but the brain stops telling them to breathe – called central sleep apnoea. “There is a pause and the person does not make any effort to breathe,” says Dr Kirk Kee, a sleep and respiratory physician at the Royal Melbourne Hospital. “That’s until their carbon-dioxide level gets high enough that their brain goes, ‘Whoops, I need to breathe again.’ ” The most common reason for this is severe heart disease, but stroke and opiates can also cause it.

Gina Bundle, who got tested for apnoea, with sleep scientist Serhan Kalistu.Credit: Photo: Paul Jeffers. Artwork Aresna Villanueva

How do you know you’ve got sleep apnoea?

It’s 9pm and patients toss and turn. Some watch TV, others scroll their phones, but it’s hard to ignore the weirdness of being in a sleep laboratory. Gina Bundle has 22 electrodes attached to pads stuck mostly on her face and head. Wires neatly run behind her back, keeping her from getting tangled, then into a monitor recording every breath and blink. “You feel it all over,” she says.

She can’t remember her last good night’s sleep. A thyroid condition then long COVID made her exhausted. She’s spending the night in the Royal Melbourne Hospital to test whether sleep apnoea has also been in the mix. “When you get home from work, you sit and take your shoes off. Well, I didn’t even get that far; I’d be out like a light,” she says.

Sleep scientist Serhan Kalistu calculates Gina’s body mass index (BMI), checks her blood pressure and measures the width of her neck – anything unusually wide carries a greater chance of apnoea. Bands around her chest and abdomen measure her diaphragm moving, as does a CPAP machine (continuous positive airway pressure) that blows air at gentle pressure into her nose. Scientists adjust the pressure during the night. “If you have sleep apnoea, you’re not actually breathing, so on the system there will be a flatline for a few seconds,” Kalistu says.

Her test results were ‘through the roof’, showing she stopped breathing 110 times every hour.

How severe a person’s sleep apnoea is depends on how often they stop breathing in an hour, a scale known as the apnoea hypopnea index or AHI. Five to 15 events is considered mild; 15 to 30 moderate; and more than 30 severe. (Susan Graham says her test results were “through the roof”, showing she stopped breathing 110 times every hour, or nearly once every 30 seconds.)

Computers in the next room chart the patients’ breathing, eye movements, heartbeat and brain waves. Some lines become more squiggly as the patient enters the deeper stages of sleep known as slow wave and rapid eye movement. The monitors also record snoring, which Kalistu has seen exceed 70 decibels, roughly the rumble of a washing machine. “In terms of the snore itself, it generally happens in our deeper sleep stages,” he says. But sleep apnoea also limits people from reaching deeper sleep. “As a result, they always wake up feeling groggy.”

It can be a patient’s bed partner, who has lost sleep listening to the silences between their companions’ bursts of snoring, who persuades them to seek a sleep test. But long gaps between breaths aren’t always noticeable or distinguishable from snoring. And for people who sleep alone, the signs of apnoea might be just tiredness, headaches or waking with a dry mouth.

The long-term effects of apnoea (we’ll get to them in a minute) worry Gina – “I’m nearly 60, I’m an Aboriginal woman, I’m in the danger zones for just about everything” – but being in a hospital similar to where she works has brought a sense of calm. “Maybe it’s because there are people around me.”

A sleep study can also be done at home, but the findings are not as granular, says David Cunnington. He will recommend these for people who are unlikely to have further underlying health problems. “It’s not that much simpler. But you go home then sleep the night and the next day you drop your equipment back.” In 2019, people aged between 65 and 74 were the most likely to do a laboratory study while those aged 45 to 64 were most likely to do a home test.

Gina Bundle, wired up in a sleep lab: “I would love normal, whatever normal is.”Credit: Paul Jeffers

How does sleep apnoea affect your health?

Melinda Mahlberg could barely find the energy to make dinner for her family in south-west Sydney. “I just wanted to lie on the lounge and go to sleep.” She was making “silly mistakes” at work such as tripping over, once getting a black eye.

It’s well known that a poor night’s sleep can reduce our cognitive performance and ability to manage emotions. But Angela D’Rozario, a research leader at the Woolcock Institute of Medical Research, says the way sleep apnoea affects cognition can differ between people, with some still able to perform tasks that others can’t. “It’s so difficult to separate people; but we think part of that is they recruit other brain regions to maintain a level of performance.”

For most people though, the risks remain, including to others. Drivers with sleep apnoea are 2½ times more likely to have an accident, says Andrew Vakulin, of the Adelaide Institute of Sleep Health. In August, a Victorian coroner found a truck driver’s undiagnosed sleep apnoea possibly contributed to his failure to stop at an intersection in Corio in Geelong; he collided with a 27-year-old driver who died as a result. State licensing authorities generally follow Austroads’ Assessing Fitness to Drive guidelines, which require people with sleep disorders to report them, depending on their symptoms. Health professionals can also advise the licensing authority of someone’s incapacity to drive.

Untreated sleep apnoea doubles the risk of heart failure, and increases the risk of stroke.

In some cases, intoxication from drugs or alcohol can blunt the reflex of people with sleep apnoea to breathe, says Cunnington. “If you already have sleep apnoea, a smaller drug overdose might be more dangerous for you.” (A Los Angeles coroner found sleep apnoea contributed to Star Wars star Carrie Fisher’s death at age 60 in 2016, although they could not state the effect of multiple drugs found in her system.)

But it’s the longer-term consequences of sleep apnoea that are a worry, too. In 2018, it played a role in 1066 deaths in Australia, accompanying heart disease in more than one-third of those cases. Untreated sleep apnoea doubles the risk of heart failure, and increases the risk of stroke. Each time a person with apnoea wakes, a stress response is triggered in their body, Cunnington says. “If you just get repeated stress responses every single night, over time that baseline is just a bit higher and blood pressure sits at just a bit higher level. The heart muscle can be weakened over the years as well.”

Sleep serves many restorative functions, too, including cleaning neurotoxins in the brain. Emerging evidence suggests sleep apnoea interrupts this, putting people at greater risk of dementia. “One of the things that’s known about the cleaning process is that if you have elevated blood pressure at night, for example, the cleaning process is somewhat compromised,” says Craig Phillips, of the Woolcock Institute and Macquarie University, who is researching dementia’s links to sleep apnoea.

Melinda Mahlberg, and with her CPAP mask on.Credit: Photo Edwina Pickles. Artwork Aresna Villanueva

How is sleep apnoea treated (and what’s a CPAP machine)?

The labourer’s apnoea was so severe he would fall asleep on scaffolding at work. It was 1980 and Sydney physician Colin Sullivan recommended the man have a procedure called a tracheoscopy, in which a tube is inserted to allow breathing through the throat. But the man refused. So Sullivan offered to do an experiment.

At the time, it wasn’t known whether sleep apnoea was due to muscles in the airway tensing or relaxing. If the latter, Sullivan had an idea: a gentle stream of pressurised air holds the airway open during sleep. “Initially, I thought this would be a rescue therapy that someone like this man, who came in with really serious complications, could use to get them on treatment,” he says. “It was absolutely spectacular. In the morning, he woke up and he was bright and alert.”

Colin Sullivan with his early CPAP machine in 1984. About 1000 patients used the machine. Credit: Paul Matthews

Now known as the CPAP machine, Sullivan’s invention is the most common treatment for sleep apnoea. Joe Biden is one user, the White House said in June after indentations were visible on the president’s face from the mask one morning. The mask can cover both airways or just the nose and attaches to a small, box-shaped machine that sits at the bedside, as quiet as a desktop computer. An expert will recommend an air pressure depending on the severity of apnoea, typically after a sleep study.

It’s “definitely not sexy”, says Susan Graham of her machine. Still, Megan Rees swears they help more relationships than they harm. “I have certainly seen relationships blossom when people start being treated and the snoring and gasping stops.”

Melinda Mahlberg’s snoring was a source of tension for her and her husband. “We’ve got friends who sleep in separate rooms and I thought, well, maybe that’s where we’re headed … because I can’t just choose to stop snoring,” she says. Troy says he sometimes rolled over to disturb Melinda to stop the snoring. “I would feel guilty for that, she would feel guilty for snoring; we were all in this big guilt cycle.”

Now Melinda is using CPAP, they’re both sleeping better, but she still has a big “sleep debt” to repay. “I’ve only been using CPAP for two months, so I’m still looking forward to the benefits.”

‘I would love normal, whatever normal is. It would be nice to go to bed and just go straight to sleep.’

In milder cases, a kind of mouth guard called a mandibular advancement splint, which repositions the jaw and tongue, can stop the airway collapsing. A specialist dentist will usually fit the device. “Some people find these more comfortable than CPAP, and they have good research to support their use,” says Cunnington. “[But] if you try to push the jaw too far, it can cause discomfort. It can also cause the teeth to shift over time.” Surgery can also help widen airways in some cases, such as for children with large tonsils. “There’s no uniform surgery; it’s an individualised approach.”

And losing weight is an option for many, although exhaustion can make you less inclined to exercise and more likely to seek out sweet snacks for energy. Several hormones that affect appetite and metabolic rate also need the deeper stages of sleep to be properly regulated. “You end up being in a vicious cycle,” says Rees. Still, one study showed people who lost 10 per cent of their body weight had a 26 per cent drop in how many times they stopped breathing while asleep.

Weight-loss drugs could be a new frontier, but the evidence is still emerging. Trials overseas of the drug, Wegovy, and a similar drug called tirzepatide with two active ingredients, have found body weight dropped by about 15 per cent and 20 per cent respectively. “We actually think it’s going to be a game-changer,” says Craig Phillips, who has evaluated the potential of the drugs. Tirzepatide is being trialled for its ability to make sleep apnoea less severe. Gastrointestinal side effects are one sticking point, but these can be offset by gradually increasing the dosage, Phillips says.

Different drugs also still in trials could prevent muscles in the throat from relaxing during sleep. If successful, these could complement existing treatments, Cunnington says. “A mouth guard plus medication might well prevent them needing to go on to CPAP.”

Sullivan isn’t concerned his machines will be displaced just yet though. “Sleep apnoea is not simply weight; [many] people probably have a relatively small airway that puts them at risk,” he says. “I honestly don’t believe we’re going to find the silver bullet.” Graham is one patient who believes she would suffer from sleep apnoea for life without CPAP. “It’s not instantaneous that you feel better; it takes a while for your body to get used to actually getting sleep again,” she says. “Now, I can’t sleep without it.”

As Gina Bundle waits for the results of her sleep test, she just wants to know what a good night’s sleep is. “I would love normal, whatever normal is. It would be nice to go to bed and just go straight to sleep.”

Get fascinating insights and explanations on the world’s most perplexing topics. Sign up for our weekly Explainer newsletter.

If you'd like some expert background on an issue or a news event, drop us a line at [email protected] or [email protected]. Read more explainers here.

Most Viewed in Lifestyle

Source: Read Full Article