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Get some sleep, and get your brain washed

One new study showed a way the brain, during deep sleep, could be cleansing itself of toxic waste. Sadly, our busy lifestyles and addiction to devices is making deep sleep more rare.

Sleep flushes toxins from the brain and reduces anxiety

Anxiety levels were higher without sleep, scientists found. (Raudies/ullstein picture/Getty )

There is no question a good night's sleep is good for your physical and mental well-being. Two recent studies add to our picture of how this works. One showed a way the brain, during deep sleep, could be cleansing itself of toxic waste. The second showed how getting enough sleep can reduce anxiety the following day. Sadly, our busy lifestyles and addiction to devices is making deep sleep more rare.

A team of neuroscientists from Boston University produced the first ever images of cerebrospinal fluid (CSF) pumping through the brain during sleep. The scientists believe the fluid flow could be literally washing the brain of toxic proteins that build up during the day. 

During sleep, blood flows out of the brain, and waves of CSF pulse through the brain, coordinated with rhythmic waves of electrical activity. Some of these proteins that the CSF is thought to pick up and remove are related to memory impairment. The team also found out that this mechanism is weaker in older people, who sleep less and less well, and so this could be involved in memory loss and Alzheimer's.

Another study at the University of California Berkeley found that a lack of proper sleep increases anxiety levels by as much as 30 per cent. It appears that sleep is a time when the brain not only cleanses itself, but when it balances its neural activity as well.

Scientists recommend ending screen time one hour before bedtime. (Credit: iStock/Getty Images)

Using a suite of brain scanning techniques, including fMRI, the researchers looked at the effects of sleep deprivation on 18 student volunteers. They found that after a sleepless night the medial prefrontal cortex of the brain, which normally controls emotions, shuts down, while deeper emotional centres in the brain were overactive. In addition, standardized testing showed their anxiety levels were higher without sleep. 

In comparison, those who got a full night of sleep, especially the deep, non-REM type, experienced the lowest anxiety the next day. Sadly, anxiety can also keep you up at night leading to a vicious circle of sleep deprivation and even higher anxiety.

Scientists suspect that sleep restores the balance between the different regions of the brain so anxiety is kept in check. Anxiety disorders are the most common mental health issues, affecting one in 10 Canadians. This raises the hope that simply getting a good night's sleep could be a non-pharmaceutical way to help combat it.

But deep sleep is becoming more difficult, partly due to the influence of electronic devices.

5 tips to improve 'sleep hygiene'

Another study out of Singapore looked at the potential impacts of early exposure to devices such as smartphones, tablets and computers on preschoolers who had been diagnosed with neurodevelopmental disorders like autism, language delays and learning disorders.

They found that the presence of multiple electronic devices in the bedroom — particularly starting as early as 18 months — among pre-school children was associated with increased sleep problems and emotional and behavioural difficulties.

The researchers also found that among the children affected, their parents also spent a lot of time on devices at home, and used devices as tools to entertain or calm the children. The scientists recommend limiting screen time at home and ending it one hour before bedtime. 

This study looked at a group of children in a particularly high-risk group for these problems, but the researchers think this could serve as a caution for all parents as similar findings have been seen in typically developing children. The American Academy of Pediatrics recommends avoiding screen time for children younger than 18 months, and particularly limiting screen use within an hour of bedtime.

As for the rest of us, there are a pretty well-known set of ways to improve your "sleep hygiene." Avoid caffeine and alcohol just before bed, try to go to bed and wake up the same time every night, keep the bedroom cool, and if you do find you can't sleep, get up and do something quiet and relaxing until you feel tired, but don't use an electronic device!

If you don't feel quite like yourself after a rough night, you're not. Your brain is cluttered with waste products, emotional responses to stress and anxiety are heightened, your judgment is impaired, you are simply not running on a full tank of gas.

Having just come from a gruelling cross-Canada trip involving stops in many cities, different hotel rooms every night, jet lag and sleeplessness, my brain feels like it is a little slower than usual. It takes a little more effort to maintain a train of th.....

About the Author

Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.


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