Lack of deep sleep from sleep apnea linked to damage in brain, study says

Uncontrolled sleep apnea - a disorder in which people stop breathing for 10 seconds or more at a time multiple times a night - may harm future brain health, a new study found.

It's estimated 936 million adults worldwide between the ages of 30 and 69 may suffer from sleep apnea, with many more people undiagnosed. If the sleep apnea is severe and untreated, people have three times the risk of dying from any cause.

People with severe sleep apnea who spent less time in deep, also known as slow-wave sleep, had more damage to the white matter of the brain than people who had more slow-wave sleep, according to the study.

White matter is the tissue that forms connections between brain cells and the rest of the nervous system. When the brain is scanned, small white spots, called white matter hyperintensities, show the extent of the damage.

For every 10% decrease in time spent in deep sleep, there was an increase of white matter hyperintensities in the brain similar to the effect of being 2.3 years older, said study coauthor Dr. Diego Carvalho, a neurologist at the Mayo Clinic in Rochester, Minnesota.

"The association with sleep apnea was only unveiled when we isolated severe cases, suggesting that mild to moderate sleep apnea may not be significantly associated with white matter changes," he said.

However, no treatment exists for such changes in the brain, "so we need to find ways to prevent them from happening or getting worse." Carvalho said.