Canadian brain scientists say they have the first good evidence that poor sleep quality might prevent the brain from being able to clear itself of toxins, by causing enlarged spaces in the brain.

The researchers with The Sunnybrook Research Institute in Toronto say their finding suggest that sleep is key to allowing the brain to rid itself of waste from brain activity.

They also suspect that having poor quality sleep over many years could have implications in brain diseases linked to brain toxin build-up, such as Alzheimer's disease.

Scientists have never really quite understood how the brain rid itself of waste. Most organs use the lymph node system to send waste into the bloodstream, but the brain does not have a dedicated waste removal system.  Instead, it uses fluid-filled channels that surround blood vessels called perivascular Virchow-Robin spaces (VRS). This brain-waste removal system has been dubbed the glymphatic system.

Courtney Berezuk, with the L.C. Campbell Cognitive Neurology Research Unit at Sunnybrook says regular daily activity causes a build-up waste and metabolites in the brain, which the brain then flushes out at night using cerebrospinal fluid.

"We go to sleep at night, the brain opens up, and the fluid is able to rush through, cleaning it out, similar to how a toilet would flush out waste… that’s a simple view of what's going on," she said.

Using MRI scans of volunteers at a sleep lab, the Sunnybrook researchers found that people who had had a bad night's sleep, getting only about three hours of sleep, had enlarged VRS brain spaces.

That suggests these spaces have become blocked and unable to clear toxins properly, says neurologist and sleep specialist Dr. Mark Boulos, the study's principal investigator and senior author.

"We believe that while one sleeps, most of the drainage of these toxins occurs.  So if one has fragmented sleep or poor quality sleep, drainage of toxins doesn't occur in such a robust manner," he explained.

While much of the research into stroke and dementia has focused on improving the health of blood vessels through healthy diet and exercise, Boulos says the role of sleep has been overlooked.

He says this research holds the promise of providing a new treatment area for people living with the effects of stroke, and possibly for dementia prevention.

“This is potentially an exciting area that should be further explored. There are a lot of connections between brain health and sleep and we're just beginning to appreciate them now,” he said.

For those who are poor sleepers, the good news is that many sleep disorders that cause fragmented, low-quality sleep – such as sleep apnea or restless leg syndrome - are treatable.

Boulos recommends that those with sleep problems talk to their doctor about their problem, and not just attribute poor sleep to age or underlying health condition. He says it's important to have sleep problems examined because poor sleep could have implications for your brain health. 

"This work emphasized the importance of good quality, uninterrupted sleep.

With a report from CTV's Avis Favaro and producer Elizabeth St. Philip