Sleep Disorders

Updated 11 August 2014

The sinister side of snoring

Sleep apnoea - usually manifest in bursts of strangled-sounding snores - plagues millions every night. It's a sleep-thief, but it's also potentially very dangerous...

Sleep apnoea - usually manifest in bursts of strangled-sounding snores - plagues millions every night. It's a sleep-thief, but it's also potentially very dangerous...

It's classed as a sleeping disorder, and it baffles experts. In all the research that's being done into what's technically called obstructive sleep apnoea (OSA), one of the messages that's coming through most clearly is this: don't dismiss snoring. OSA can be fatal, and early diagnosis makes all the difference.

What is it?

OSA occurs when a blocked airway repeatedly halts the sleeper's breathing, resulting in loud bursts of snoring and, because sleep is so disturbed chronic daytime fatigue (for the sufferer, as well as for their suffering sleeping partner).

Among risk factors is obesity, so losing weight is often the first recommended response. Avoiding alcohol and quitting smoking can also offer a measure of relief.

Early studies linked OSA to a higher risk of stroke, heart disease and diabetes.

OSA linked to memory loss

In one of the most surprising recent studies on OSA, researchers discovered that people with sleep apnoea showed tissue loss in brain regions that help store memory.

The findings demonstrated that impaired breathing during sleep can lead to a serious brain injury that disrupts memory and thinking.

This study focused on structures called mammillary bodies (they resemble small breasts, on the underside of the brain). The researchers scanned the brains of 43 sleep apnoea patients, using magnetic resonance imaging (MRI) to collect high-resolution images of the entire brain, including slices of the mammillary bodies.

When they compared the results to images of 66 control subjects matched for age and gender, the scientists discovered that the sleep apnoea patients' mammillary bodies were nearly 20 percent smaller, particularly on the left side.

So what does this mean? Well according to the lead researcher, Rajesh Kumar, the findings are important because patients suffering memory loss from other syndromes, such as alcoholism or Alzheimer disease, also show shrunken mammillary bodies.

Researchers hypothesised that repeated drops in oxygen lead to the brain injury. During an apnoea episode, the brain's blood vessels constrict, starving its tissue of oxygen and causing cellular death. The process also incites inflammation, which further damages the tissue.

According to neurobiologist Ronald Harper, "The reduced size of the mammillary bodies suggests that they've suffered a harmful event resulting in sizable cell loss. The fact that patients' memory problems continue despite treatment for their sleep disorder implies a long-lasting brain injury."

In other recent research findings:

-- Driving: It turns out one spin-off of impaired waking quality of life, involves driving: OSA sufferers can be bad drivers. Research conducted in Canada showed that people with OSA are nearly five times as likely to get into car accidents in which people get hurt than. And the more severe the sleep apnoea, the greater their risk.

With this in mind, research was conducted involving what is called continuous positive airway pressure: during sleep, a person wears a mask that pushes oxygen into the lungs. It worked: the risk of crashes was reduced, and awareness was improved.

-- Surgical complications: A US study of 172 patients with features of sleep apnoea showed that the OSA may put them at an increased risk of developing complications after elective surgery.

Nine patients had breathing complications after surgery, five had cardiovascular complications, two had bleeding complications and one developed gastrointestinal complications. These figures were significantly higher than among the equivalent number of patients who didn't suffer from OSA.

Sources: Reuters Health; SAPA, EurekAlert


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Sleep disorders expert

Dr Alison Bentley is a general practitioner who has consulted in sleep medicine and sleep disorders, in both adults and children of all ages, for almost 30 years. She also researches and publishes on a number of sleep-related topics both in formal research journals and lay publications including as editor of Sleep Matters, an educational newsletter on sleep disorders for doctors.

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