It has ruined many a night鈥檚 sleep, and no doubt a lot of relationships too. Trying to sleep next to a snoring partner is exactly that: trying. Once the engines fire up, there are few countermeasures besides a shove, earplugs and the patience of a saint.
That鈥檚 the thing about snoring: many of us consider it to be little more than an embarrassment or an annoyance and grudgingly put up with it. But accumulating findings suggest that this trivialises an important, and common, health problem.
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Snoring isn鈥檛 just associated with broken sleep, it can be a warning sign of trouble ahead and also appears to have some potentially serious impacts on the snorer鈥檚 cardiovascular system. Despite a proliferation of remedies, there is a paucity of evidence about what works. But as sleep researchers increasingly wake up to the hidden dangers of snoring, there is hope the nightmare will soon end.
Snoring is very common, though getting a handle on exactly how common is difficult. Many snorers are blissfully unaware that they do it. 鈥淚f you ask someone 鈥楧o you snore?鈥�, they鈥檒l say 鈥業 dunno, I鈥檓 sleeping鈥�, 鈥� says , director of sleep health at Flinders Health and Medical Research Institute in Adelaide, Australia. 鈥淭heir bed partner might tell them, but a lot of people don鈥檛 have a bed partner.鈥� In Eckert鈥檚 experience, however, it is rampant. 鈥淚t鈥檚 a huge problem,鈥� he says. 鈥淭he main reason people come to our clinic is snoring.鈥�
Most formal estimates of the prevalence of snoring rely on self-reports, or those from bed partners, and vary widely in their findings, with numbers as low as and as high as 83 per cent in others. But two are that about 45 per cent of adults snore occasionally and 25 per cent snore regularly. Men are more likely to snore than women and the incidence rises with age and body mass index. Drinking alcohol, taking sleeping pills and sleeping on your back amplify the problem.
Causes of snoring
For anyone unfortunate enough to be within earshot, a snore is a snore is a snore. From a medical perspective, however, there are two categories of snorer in this world. One is people who have sleep-disordered breathing conditions such as obstructive sleep apnoea (OSA) or hypopnoea. These conditions are usually caused by the squishy anatomical structures of the upper airway collapsing under gravity. As air passes over these tissues, they vibrate noisily.
The tissue around the top of the throat may fully (in the case of OSA) or partially (in the case of hypopnoea) obstruct the windpipe, which can lead to dangerous reductions in a person鈥檚 blood oxygen levels. People with severe OSA can stop breathing altogether hundreds of times per night.
Snoring is often a symptom of these disorders, but not always. Indeed, about . Those in this second group are classified as 鈥減rimary鈥� snorers. The cause of their snoring is also sagging airways, but the tissue doesn鈥檛 frequently interfere with the business of getting air into the lungs. The it as snoring with an average of four or fewer episodes of apnoea or hypopnoea per hour of sleep 鈥� many times fewer than those with serious OSA.
How bad is snoring for your health?
While OSA has long been associated with various cardiovascular diseases, especially strokes, primary snoring was seen as much less of a threat. The most well-recognised health consequences of primary snoring included , irritability, and decreased cognitive performance. , especially in the ear facing the snorer.
But there is more to snoring than just a bad night鈥檚 sleep. For a long time, heavy snoring has been known to be associated with a disease called carotid atherosclerosis, where solid plaques build up on the insides of the main arteries in the neck. This is a major risk factor for strokes because pieces of plaque can come loose, float into the brain and block smaller blood vessels. The association was assumed to be with OSA, however, rather than primary snoring.
That changed in 2008 when researchers at the Westmead Institute for Medical Research in Sydney, Australia, examined the carotid arteries of a group of primary snorers and non-snorers. They found that ; the heavier they snored, the more likely they were to have it. Around two-thirds of the very heavy snorers 鈥� those who snored for more than half of a typical night鈥檚 sleep 鈥� had carotid atherosclerosis.
The researchers also examined the femoral arteries in the snorers鈥� thighs and found no sign of atherosclerosis, pointing to the conclusion that the carotid problem was specifically associated with snoring.
There was already a suggested mechanism for this: the carotid artery runs close to parts of the anatomy that vibrate during snoring and may be damaged by repeated exposure to mechanical stress. So the team exposed the carotid arteries of anaesthetised rabbits to 6 hours of snoring-like vibrations. , which is a known precursor of atherosclerosis.
The results prompted Jeremy Rich, then at the Walter Reed Army Medical Center in Washington DC, and his colleagues to dig deeper. They obtained a database containing more than 77,000 assessments of habitual snorers under investigation for OSA. Most of the people in the database did indeed have OSA, but about 6000 of them didn鈥檛 鈥� and they were still at a higher risk of death.
Even when the researchers excluded those with the additional risk factor of obesity, the than expected. Exactly why was unclear. The link to carotid atherosclerosis was a possibility, as was the fact that many primary snorers have some episodes of apnoea or hypopnoea, albeit not often enough to get over the diagnostic threshold. Primary snoring can be the start of full-blown OSA or hypopnoea: some snorers in the study may have gone down that road after the test.
Noise levels
Since then, the noise levels around the health hazards of primary snoring have ratcheted up. In 2018, a , finding that primary snorers were more likely than non-snorers to have one of its symptoms: stenosis, or narrowing, of the carotid artery.
Another area of concern is metabolic syndrome (MetS), a dangerous combination of obesity, high blood pressure, abnormal lipid levels in the blood and high blood sugar. OSA is a known risk factor for MetS, but primary snoring is emerging as one too. The first hints of a connection came in the and the . In 2020, a team at Shanxi Medical University in Taiyuan, China, evidence and concluded that primary snoring is clearly associated with MetS, though the direction of causality is unclear. It is possible that metabolic syndrome or its components cause snoring and not the other way around. People with higher BMI are more likely to be snorers, for example.
But one component of MetS is emerging as a particular worry for primary snorers: high blood pressure, or hypertension, which is a . In 2018, Serge Brand at the University of Basel in Switzerland and his colleagues of 181 adults aged 40 to 60 who had been referred to a sleep clinic at Kermanshah University in Iran because of difficulties breathing while asleep. They all spent a night in the sleep lab to be assessed for OSA and have their blood pressure measured.
When the researchers crunched the numbers, they found that those who were diagnosed with OSA were more likely to have hypertension. But so were primary snorers.
The study was admittedly small, but a much larger dataset confirms this finding. Earlier this year, a team led by Eckert鈥檚 colleague , also at Flinders Health and Medical Research Institute, recruited more than 12,000 middle-aged people, mostly men, who had suspected OSA. Crucially, the participants were already using a , which sat under their mattress at home and kept tabs on snoring and probable episodes of apnoea and hypopnoea. They were also keeping track of their blood pressure.
Snoring isn't just associated with broken sleep, it can be a warning sign of trouble ahead
Devices such as these are revolutionising the study of primary snoring, says Eckert. Before they came along, snoring was hard to get good data on, even during OSA assessments in a sleep lab. 鈥淲e didn鈥檛 measure snoring very well or quantitatively,鈥� he says. 鈥淚t was largely just, did they snore, yes or no? So we haven鈥檛 been able to ascertain the role of snoring in and of itself with any degree of certainty.鈥� But home devices have made it possible to gather that information.
Lechat鈥檚 team gathered around six months of data from each participant. Around 20 per cent of them had high blood pressure, defined as an average systolic/diastolic reading of 140/90 mmHg or above. In many cases, the hypertension could be linked to OSA, which was to be expected. When the researchers eliminated people with OSA, however, they found that primary snorers also tended to be hypertensive 鈥� they were almost twice as likely as non-snorers to exceed the 140/90 threshold. On average, their . This is clinically significant, says Lechat: for people aged 40 to 69, an increase in systolic blood pressure of 20 mmHg, or diastolic blood pressure of 10 mmHg, .
The direction of causality still isn鈥檛 fully established, but it is telling that the primary snorers with high blood pressure were younger and slimmer than the average participant, says Eckert 鈥� so their hypertension couldn鈥檛 be solely attributed to their age and body mass.
There are many plausible mechanisms by which primary snoring could cause hypertension, says Eckert. 鈥淵ou鈥檙e still getting the airway muscles and structures relaxing and narrowing. Maybe it鈥檚 not enough to make your oxygen levels go too low, but you鈥檙e still placing extra strain on the heart and the breathing muscles and that can add up to raised blood pressure.鈥� On top of that, atherosclerosis is also a cause of hypertension because it narrows the arteries. 鈥淪noring may be an important mechanism that contributes to hypertension,鈥� concluded Lechat and his colleagues in their paper on the study.
It could also be at least partially down to something entirely different: noise exposure. This is often measured with 鈥淎-weighted decibels鈥�, or dB(A), which is a more accurate representation of the wavelengths at the middle of the human hearing range. , nighttime sound levels in excess of 45 dB(A) 鈥� about the same as a 鈥� , which has been identified as a . Regular exposure to nighttime noise pollution in excess of 53 dB(A) can directly , possibly as a result of increased levels of stress hormones.
Snorers regularly smash these sound barriers. published in 2019 found that two-thirds of habitual snorers exceed 45 dB(A) and 14 per cent go higher than 53 dB(A). , the loudest snore ever recorded was 93 dB(A). 鈥淭his is incredibly loud, starting to get to jackhammer level,鈥� says Eckert.
The next step for the Flinders team is to treat primary snoring and see whether it lowers blood pressure, he says. If it does, then the arrow of causality will be firmly pointing at snoring as an independent cause of hypertension. For now, says Eckert, snorers would be well-advised to get their blood pressure checked.
Remedies for snoring
All of which points to an urgent need to find suitable remedies. For OSA, the solution is sometimes surgery, but what can be done for primary snorers? In 2023, the Australasian Sleep Association issued , which included weight loss, cutting down on alcohol, sleep-position training to get snorers off their backs and bespoke mouthpieces to open their airways. More drastic measures requiring medical supervision are continuous positive airway pressure (CPAP), a ventilator-like device that keeps the airways open, and, as a last resort, surgery to the nose or soft palate to trim back the tissues that create snoring.
These are all commonly prescribed treatments, says Eckert. So is quitting smoking. But none has especially strong evidence behind it. And many of the other options on the anti-snoring menu are even less validated. 鈥淭here鈥檚 a heap of rubbish out there,鈥� he says.
Earlier this year, , then at the University of York in the UK, and his colleagues carried out a investigating potential interventions. They didn鈥檛 assess the strength of the evidence, but found some gaping holes in the literature. One was that there was no research whatsoever on the effectiveness of weight loss, cutting down on alcohol and quitting smoking.
Bed partners are at risk of hearing loss, especially in the ear facing the snorer
鈥淪everal behavioural interventions have not been assessed, even though they have long been widely advisable for snorers,鈥� says Changsiripun, now at Chulalongkorn University in Bangkok, Thailand. Another was that very few of the studies assessed the impact on snorers鈥� sleeping companions, even though 鈥渂ed partners are often the most impacted by snoring鈥�, says team member Catriona McDaid at the University of York.
This general paucity of evidence is probably down to the fact that primary snoring isn鈥檛 鈥� yet 鈥� seen as a major health hazard, says Eckert. If it were, there would be more research on how to stop it.
For now, the snoring-afflicted will need to make do with the little available evidence. But Changsiripun is on the case. 鈥淥ur findings will support future systematic reviews to compare all treatment options for efficacy and safety,鈥� he says. 鈥淭hus, for those interested in which treatments have the strongest evidence for the best-suited therapy, please stay tuned for more definitive conclusions.鈥�
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