THE EXACT REASON WHY WE SLEEP ONE-THIRD OF OUR LIFE has long been one of the greatest and enduring mysteries of modern science. Many different theories and concepts have been proposed, but the reality check is that no one is entirely sure why we spend roughly a big part of our lives asleep.
What happens to your body when you fall asleep is known to many, but what happens to your brain is still researched?
Scientists and sleep researchers are still chasing the elusive question of why our brains need sleep. Thanks to new emerging technologies and real-time brain scan tools are shedding more light on what is happening to our brain in the sleep world.
In one such experiment, sleep researchers sleep-deprived themselves to uncover the effect of sleep in the detoxification of the brain.
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What Was the Experiment?
There was a study published in the journal Science on Oct 31, 2019, which was landmark and ground-breaking by all means. Before that neuroscientist, Laura Lewis and her team of researchers at the Boston University Lab were for the past few months were putting in late nights running a few tests.
Sometimes it would take them 3.00 AM to finish experimenting with their test subjects. The entire team was working hard to find out what happened to the brain during sleep. To uncover the sleep secrets on the brain, Laura’s team brought 13 voluntary participants between the age group of 23 to 33 into their Boston Lab.
The participant’s task was somewhat unique and difficult: they had to sleep inside an extremely noisy MRI machine wearing EEG caps to measure their brain waves while asleep.
“We have so many people who are really excited to participate because they want to get paid to sleep,” Laura Lewis says with a chuckle. “But it turns out that their job is actually–secretly–almost the hardest part of our study. We have all this fancy equipment and complicated technologies, and often a big problem is that people can’t fall asleep because they’re in a really loud metal tube, and it’s just a weird environment.”
The team measured out the brain, brain waves with EEG, and blood oxygenation with functional MRI measuring which measures blood flow in the brain (and thus brain activity), before and during sleep and the corresponding changes in blood-oxygen-level, and the CSF flow in the brain. Their main purpose was to measure the velocity of CSF (cerebrospinal fluid) flow into the brain.
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What is CSF?
Cerebrospinal Fluid (CSF) is a colorless liquid that washes your brain and spinal cord. Behind the cleaning, action is the main objective of protecting the brain and acting as a shock absorber. It acts as an excellent waste disposal agent removing waste products, antibodies, and harmful chemicals from the brain.
The Interesting observation:
When the subjects were awake, small, and gentle waves of CSF entered the brain about every 4 seconds. But to their surprise when the subjects were asleep, the researchers discovered, large waves (like tsunamis) of CSF flow in and out of the brain every 20 seconds. “The waves we saw during sleep were much, much larger, and higher velocity,” says Lewis.
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The Logic behind the reason.
According to Experts, one of the explanations may be that during slow-wave sleep (SWS or Stage iii) neurons turns off. Since the neurons momentarily stop firing and switch off, they require far less oxygen.
That means blood flow to the brain decreases and a vacuum is created. In response to the vacuum (absence of blood), pressure in the brain drops, and CSF rushes into the space left behind to maintain pressure at a safe level.
When we are awake, not all neurons turn off at the same time, so blood levels in the brain don’t drop enough to allow this huge wave of CSF to move around and enter the brain. This process clears out all cellular trash like beta-amyloid, tau, and other toxic molecules.
In short, the brain’s inherent ‘plumbing system’ gets activated, CSF acting as a delivery agent pick-up the waste accumulated in brain cells and throws it away thus clearing unwanted debris. This amazing garbage collection system not only disposes harmful toxic molecules from the brain but also helps clean and maintain the brain at the cellular level.
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Implications of the Findings.
These ground-breaking findings, experts agree have great implications for neurodegenerative diseases. The importance of sleep-in removing wastes and clearing out toxins from the brain- including beta-amyloid, metabolic by-products, and tau (a protein that gets tangled in Alzheimer’s patients’ brains and harms the connections between neurons) will contribute greatly to the understanding and addressing diseases such as Alzheimer’s, dementia and Parkinson’s. It would open new avenues for treating and preventing neurodegenerative diseases.
It has been observed that patients with Alzheimer’s have fewer and weaker slow brainwaves. And since the flow of CSF is directly proportional to the frequency of slow waves, there are smaller waves of CSF in their brains, thus impacting their waste clearance pathway. And also, as you get older, your brains shrink and produce less of the fluid with increasing age, which may slow its circulation.
Research in sleep science has shown that during a good night’s sleep, the human body goes through four stages of sleep. Three stages of non-REM sleep, followed by the dreaming stage of REM (Rapid eye movement). It is during the third (N3) non-REM stage of sleep also called slow-wave sleep (SWS) that neurons experience slow oscillations in brain activity. The slow-wave sleep stage also called delta sleep or deep sleep has been associated with memory retention and consolidation.
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Also, almost 70% of the growth hormone in men is secreted during this stage. The brain activity in this stage displays a pattern of delta waves. These brainwaves have proven to play a key role in consolidating memories while we sleep.
The researchers found that the delta waves coincided with blood flowing out of the brain, which they say helps balance the total volume of fluid around the brain. So, during this stage of sleep, both body and brain enter repair and recovery mode. But the fact, that this process if also linked to brain detoxification remained unknown until this study.
Why do different animals have different sleep hours?
If this question of why different animal species require different amounts of sleep per night has puzzled you, then this study can help find the answer. For example, cats sleep for close to 12 hours, dogs need at least 10 hours, humans need 8 hours and elephants need only 3 hours.
Scientists speculate that this different sleep pattern may be related to brain size. The larger the brain, the larger the volume of space between cells, and thus have enough room for waste to collect that needs less time to clean as the flow increase substantially.
In another experiment researchers observed that sleep causes the brain cells to shrink thereby increasing the space cells by almost 60%, allowing the flow to increase. So, during sleep, the CSF flushes through the brain very broadly and quickly.
So, don’t think if an elephant can do well with just four hours of sleep, even you can do. The reason being an elephant brain is 3 times larger than a human brain.
Final words before you sleep.
Tonight, when you will sink into a deep sleep, something amazing and intriguing will happen behind your closed eyes. Your brain’s plumbing system will become on.
A slow electric wave will flow through the brain. Then your neurons will not fire and switch off. A few seconds later, the amount of red blood within the brain will drop and flow out of your brain. Then a wave of liquid called cerebrospinal fluid will reverse its usual direction of flow and moves upward through the brain. The toxic waste that you accumulated throughout the day will be cleared.
So finally, when you will wake up in the morning, you’ll feel rejuvenated and reenergized. Hope you’ll take your sleep seriously.
No matter what advancements in technology and science emerge in the next 1,000 years, a good night’s sleep can never have any alternative.
It is ironic that sleep researchers have to sacrifice their sleep to study the benefits of sleep on the human body and brain. Isn’t it!
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