A sleep disorder that leaves sufferers gasping, snorting and snoring may be caused by too much fat in the tongue, research suggests.
Known as sleep apnoea, it occurs if a person’s airways become too narrow while they slumber, causing their breathing to stop and start.
It has been linked to obesity, smoking, alcohol, sleeping on your back and even having a large neck, according to the NHS.
Now, research from the University of Philadelphia suggests a fatty tongue may be to blame.
In a study of 67 apnoea sufferers, scientists found losing weight - specifically from the tongue - relieved the condition.
“You talk, eat and breathe with your tongue - so why is fat deposited there?,” study author Dr Richard Schwab said.
“It's not clear why - it could be genetic or environmental - but the less fat there is, the less likely the tongue is to collapse during sleep,” the BBC reported.
Sleep apnoea is thought to affect 1.5m adults in the UK, of which up to 85% are undiagnosed, British Lung Foundation statistics show.
In the US, 22m are said to suffer, with 80% of moderate and severe cases going unnoticed, according to sleepapnea.org
Short-term, sleep apnoea can trigger fatigue, mood swings and poor concentration, the NHS reports.
Left untreated, it can lead to high blood pressure, stroke and depression.
Obese people with sleep apnoea have been shown to have higher amounts of tongue fat.
Weight loss is known to improve the condition, however, exactly why this occurs was unclear.
To learn more, the scientists looked at 67 obese people with an apnoea-hyponea index (AHI) of at least 10 per hour.
AHI is the total number of pauses in breathing plus the periods of shallow breathing, sleepapnea.org reports.
Harvard defines an AHI of five-to-14 as mild.
The participants were helped to lose weight, either via lifestyle measures or bariatric surgery.
Before and after, MRI scans measured the fat and soft tissue in their upper airways and abdomen.
Results, published in the American Journal of Respiratory and Critical Care Medicine, show the participants who lost 10% of their overall body weight, saw their apnoea symptoms improve by 30%.
By examining the participants’ upper airways, the scientists found shedding the pounds reduced fat in their tongue, as well as the muscle that controls chewing.
“Now we know tongue fat is a risk factor and sleep apnoea improves when tongue fat is reduced, we have established a unique therapeutic target that we've never had before,” Dr Schwab said.
Treatments that target tongue fat should be considered for sleep-apnoea sufferers, the scientists claim.
Mild cases often do not require intervention, however, more severe sufferers currently rely on a CPAP machine, according to the NHS.
This gently pumps air into a mask a patient wears over their nose and mouth while they sleep.
It prevents airways getting too narrow, aiding breathing.
A gum-shield like device does a similar job.
Lifestyle tips include losing weight if necessary and nodding off on your side, as well as not smoking, drinking excessively or taking sleeping pills unless recommended by a doctor.