Nearly everyone snores occasionally, but about one in four adults are regular snorers, and for them, there may be negative health consequences. New research from experts at Flinders University has shown that people who snore a lot, particularly middle-aged, overweight men, are more likely to have elevated blood pressure and uncontrolled hypertension.
The large-scale study, involving more than 12,000 participants worldwide, has been made possible by the development of new sleep technology. Previously, researchers mostly relied on people evaluating their own snoring or brought smaller numbers of participants into a sleep centre for assessment. Now, for the first time, researchers have been working with an under-the-mattress sensor designed for home use.
“It measures your breathing through the movement of the rib cage and also records how much you snore,” says lead author Bastien Lechat, who trialled the device and discovered that he snores only if he’s very tired or has drunk alcohol.
Snoring is basically the sound of obstructed breathing. The extra effort it takes to draw air through a narrowed airway makes tissues vibrate. This can be exacerbated by a range of things, including poor muscle tone in the throat and tongue, bulky throat tissue or a long soft palate. If you are overweight, a middle-aged man or a post-menopausal woman, you are more likely to be a snorer.
The Flinders study found that 15% of all participants, who were primarily overweight men, on average snored for more than 20% of the night. The more time spent snoring, the greater the increase in uncontrolled hypertension.
Snorers were at the same risk as those who didn’t snore but suffered from sleep apnoea (a sleep disorder in which breathing stops and starts). When both were combined, the risk was even greater.
Previous work by the Flinders team sparked a book by the late Michael Mosley, featured here. This latest study is the first to associate snoring alone with higher blood pressure and uncontrolled hypertension.
The researchers are still trying to pinpoint why snoring makes blood pressure rise. Unlike sleep apnoea, with its interrupted breathing, snoring doesn’t generally cause blood oxygen levels to fall. But it does mean the body has to work harder to take in enough oxygen. “To breathe the same amount of air, you need to put in two, three times, even 10 times more effort,” says Lechat, “and that might lead to negative pressure swings near the heart and cause some stress.
“There are two other theories that are plausible. If you snore, it can disrupt your general sleep quality, and that itself has been associated with higher blood pressure and cardiovascular disease. The other potential mechanism is that the vibration happening in the upper airway, which includes the nearby arteries, might cause inflammation.”
If you are aware that you snore regularly – or your partner is telling you so – then Lechat suggests you may want to have your blood pressure checked. If there are other symptoms, such as daytime sleepiness, morning headaches and lapses in concentration and memory, then it is worth being screened for sleep apnoea. This can be done at home using a wearable sensor.
Treatments to help reduce snoring include wearing a mouthpiece that gently pushes the jaw forwards, opening the airways. Alternatively, sufferers of sleep apnoea may want to invest in a CPAP (continuous positive airways pressure) machine. This device delivers continuous pressurised air through tubing into a mask you wear while you sleep.
“We know it helps improve quality of life, depression and fatigue and reduces the risk of accidents, but there’s still a lot of debate about whether CPAP reduces the cardiovascular risk,” says Lechat.
The participants in his study had bought the sleep sensor mats themselves, perhaps because they were concerned about their health or were the type of people who enjoyed self-tracking. They weren’t a very diverse bunch and there was no other health or lifestyle information to add to the picture that might explain the higher blood pressure measurements.
He is working towards further research, this time with a smaller number of recruited participants. The plan is to treat snoring with a mouthpiece and see if that prevents elevated blood pressure. If it does, this would present stronger argument for investing more widely in treatments to prevent it.
