Wish To Cleanse Your Brain Of Toxins? Get Your ZZZs

By

CCSS NAS-6 680 Words 5-Minute Listen
Scientists have discovered that sleeping helps our brain get rid of toxins (Credit:Joyell VanGelder/CC-SA-2.0/Pixabay)

Though considered a waste of time by some, sleep is essential for the health and wellbeing of humans. Over the years, researchers have found sleeping allows the body to repair and restore cells, get rid of irrelevant memories, and even help kids grow taller and obtain better grades. Now, it appears that snoozing for an average of 8 hours daily enables the brain to cleanse itself and get rid of harmful toxins.

The latest research follows up on a 2013 study, which found a dramatic increase in the flow of cerebrospinal fluid (CSF) in the brains of rats and baboons during sleep. The fluid helped wash away harmful waste proteins accumulated in their brain cells during the day. The process acts a bit "like a dishwasher," said Dr. Maiken Nedergard, a neuroscientist at the University of Rochester who led the 2013 effort.

Since one of the waste products removed from the mammals' brain was beta-amyloid, a substance that forms a sticky plaque associated with Alzheimer's, Nedergard wondered if his findings could offer a new understanding of the progressive disorder, which causes human brain cells to degenerate and die. Though the idea was certainly plausible, further research needed to be conducted to verify that human brains "cleanse" in a similar fashion.

During deep sleep, waves of cerebrospinal fluid (blue) coincide with temporary decreases in blood flow (red). Less blood in the brain means more room for the fluid to carry away toxins, including those associated with Alzheimer's disease (Credit: Fultz et al., 2019)

A team of scientists led by Dr. Laura Lewis, an assistant professor of biomedical engineering at Boston University, recently set out to do just that. To observe the brain during sleep, the researchers asked the study's 13 participants to eschew their comfortable beds and instead spend the night sleeping inside an MRI machine. Each person was also required to wear an EEG (electroencephalography) cap. The MRI machines allowed the scientists to measure the brain's blood oxygen and cerebrospinal fluid levels, while the EEG caps enabled them to monitor its electrical currents. "We had a sense each of these metrics was important, but how they change during sleep and how they relate to each other during sleep was uncharted territory for us," Dr. Lewis remarked. To emulate a realistic sleep cycle, the tests were conducted at midnight, and the subjects were asked to stay up late the night before to ensure they would drift into a deep sleep during the process.

The scientists, who published the results of the study in the journal Science in late 2019, found that similar to rats and baboons, large waves of cerebrospinal fluid washed through the participants' brains during non-REM sleep, the deepest part of the cycle. Even more interesting, the EEG readings showed that during this time, neurons started to turn off and on in a synchronized fashion. "There would be this electrical wave where all the neurons would go quiet," Dr. Lewis said. The halt in neuron activity caused less blood to flow into the brain, creating more room for the "cleansing" cerebrospinal fluid. The researchers are not sure how brain waves, blood flow, and CSF coordinate so perfectly. They speculate that as the blood leaves, pressure in the brain drops, and CSF quickly flows in to maintain a safe level of pressure.

During sleep, the brain's neurons momentarily stop to slow down the blood flow, enabling the CSF to flow in and cleanse the brain (Credit: Fultz et al., 2019)

Since patients with Alzheimer's have been observed to have less frequent and weaker brain waves, the researchers suspect that poor sleep in patients with neurological disorders may be impacting the brain's cleansing process and causing toxins to accumulate, eventually leading to degeneration.

"So we might expect that there are also fewer and smaller waves of cerebrospinal fluid in those disorders, and that might have an impact on how waste products are cleared," Dr. Lewis says. "We're running new studies to test how these CSF waves may change in healthy aging and in neurological disorders. We're also going to test whether this would be associated with less waste removal from the brain during sleep in these patients."

William Jagust, a professor of public health and neuroscience at the University of California, Berkeley, who was not involved in the study, believes the findings also suggest that people can reduce their risk of brain disorders like Alzheimer's by ensuring they prioritize high-quality sleep. So be sure to get your zzzs!

Resources: NPR.org, Wired.com, www.bu.edu

Get the Workbook for this article!

Workbook contains: Article, Reading Comprehension, Critical Thinking Questions, Vocabulary in Context (+ answers), Multiple Choice Quiz (+ answers), Parts of Speech Quiz (+ answers), Vocabulary Game (+ answers)
Cite Article
224 Comments
  • puppy1lover1234
    puppy1lover1234Monday, April 12, 2021 at 7:56 am
    LOOOOVVVVEEE this
    • kk2011
      kk2011Wednesday, March 10, 2021 at 6:33 am
      I LOVE TO SLEEP
      • sydney_zepp
        sydney_zeppWednesday, December 16, 2020 at 8:49 am
        I only got 5 hours of sleep last night I was awake until 1 am. Because I was drawing a picture of my sister
        • therealsnakes
          therealsnakesWednesday, December 16, 2020 at 5:40 am
          Amazing
          • animallovinggal
            animallovinggalTuesday, December 15, 2020 at 4:38 pm
            Lol love the the dog pic!
            • kurz
              kurzFriday, December 11, 2020 at 7:48 am
              I love sleeping!!!
              • kurz
                kurzFriday, December 11, 2020 at 7:49 am
                Now I have an excuse to sleep in class!!!
              • maria_goodvibes
                maria_goodvibesThursday, December 10, 2020 at 12:43 pm
                I want to take a nap, like if u want to take a nap too!
                • lilabug
                  lilabugWednesday, October 21, 2020 at 9:41 am
                  I definitely need more sleep! 😊
                  • just11
                    just11Friday, August 21, 2020 at 6:02 am
                    i need to sleep more too. im tired
                    • wolfieland
                      wolfielandFriday, July 10, 2020 at 7:46 am
                      i perfect excuse to sleep more!