While spouses of rafter-rattling snorers may occasionally think murderous thoughts, snoring is seldom fatal.
But when snoring is a sign of sleep apnea, a condition that causes breathing to be interrupted repeatedly during the night due to airway obstructions, it can signal some dire consequences.
Researchers are certain that obesity is a major contributor to sleep apnea, but studies have also found that the condition leads to high blood pressure, stroke, heart disease and diabetes, among other problems.
A report in the journal Diabetes Care in June noted that out of 306 obese patients with type 2 diabetes, testing found that 87 per cent of them also had obstructive sleep apnea, although most of them did not know it.
More than half of those tested stopped breathing between 16 and 20 times per hour (moderate apnea) or more than 30 times an hour (severe).
But the sleep-obesity loop is even more complicated.
Researchers at the University of California, San Francisco, studying more than 200 people with sleep-related breathing disorders, found that as their conditions worsened, they actually burned more calories when they were at rest.
This is not the way nature intended. We’re supposed to burn fewer calories when resting.
The findings, along with other research, support the notion that disrupted sleep patterns disrupt hormones and metabolism over time and contribute to obesity and diabetes.
Even a temporary onset of apnea, which often occurs in pregnant women, can cause problems.
Researchers at Northwestern University reported last summer that women who were frequent snorers during pregnancy were about four times more likely to develop gestational diabetes than those who did not snore.
About four per cent of pregnant women develop gestational diabetes, in which a woman without previously diagnosed diabetes develops high blood-sugar levels during pregnancy.
This often leads to larger-than-normal babies and birth complications, as well as a greater risk of the infant having low blood sugar, metabolic problems and obesity later in life. Gestational diabetes usually dissipates after the woman gives birth.
Of course, most doctors tell people with sleep apnea that the best treatment in the long run is to lose weight. But only recently did scientists — at Temple University and six other centers — put the advice to a rigidly controlled test, with results published earlier in September.
Half of nearly 300 participants with sleep apnea and diabetes went into a group behavioral weight-loss program that included portion-controlled diets and prescribed 175 minutes of exercise a week.
The control group got three lectures on diabetes management, diet and physical activity over the yearlong study.
The first group lost an average of 24 pounds, and 13.6 per cent of the group had complete remission of sleep-apnea symptoms, compared with about 3.5 per cent of the second group, which lost an average of 1 pound.
Other research shows that sleep disruption can also set the brain up for disease.
A mouse study reported last week by the Washington University School of Medicine found that chronic sleep deprivation makes the brain plaques that characterize Alzheimer’s disease appear earlier and more often.
Medical professionals treating Alzheimer’s, Parkinson’s disease and other neurodegenerative illnesses have long noted that many patients experience disturbed sleep.
But until recently, it was thought that sleep disruption was more a byproduct of disease than a contributor.
By some estimates, as many as 70 per cent to 80 per cent of dementia patients also suffer from sleep apnea.
And scientists at the University of California, San Diego, last year showed for the first time that treating sleep apnea in patients with Alzheimer’s actually seemed to improve cognitive function.
Specifically, putting patients with mild to moderate Alzheimer’s and sleep apnea on a machine that delivers pressurized air into the lungs during sleep over the course of six weeks resulted in improved test scores for things like verbal learning and mental processing.
While the mouse study indicates that sleep disruption may actually accelerate the disease process, the California scientists said the improvements they registered could simply be the result of improved oxygen levels in the brain and a clearer mind as a result of getting a better night’s sleep.
Earlier studies in adults with sleep apnea, but no dementia, have also shown improvements in mental function after receiving the pressurized air therapy.
Lee Bowman is a health and science writer for the Scripps Howard News Service.