Dubai, United Arab Emirates – For decades, scientists have been thinking about a fundamental problem. It is how the human brain gets rid of the waste it secretes while working and thinking throughout the day.
This waste contains excess proteins and molecules that may turn into toxic substances if not disposed of.
Among them are amyloid beta and tau proteins, which are considered the main causes of Alzheimer’s disease.
As for the rest of the body’s organs, the lymphatic system gets rid of this waste.
Excess fluid travels to the spleen, lymph nodes, and other parts of the lymphatic system. Then it passes into the bloodstream for disposal.
But this vital process cannot take place in the same way inside the brain.
Because of what is known as the barrier between the brain and the blood. This barrier is a protective covering that prevents the transmission of infection to nerve cells within the brain.
But it also prevents anything from being transmitted outside the brain.
In 2012, a research team at the University of Rochester, led by neurologist Maiken Niedergaard, discovered a previously unknown periodic system. This system is for expelling toxic waste from the brain.
Research on laboratory mice has shown that cerebrospinal fluid flows into tunnels around blood vessels in the brain.
These channels pass through a type of brain cell known as astrocytes. They mix with what is known as “interstitial fluids”.
It collects waste and carries it outside the brain through the spaces around the blood vessels.
Brainwashing theory
In 2013, Niedergaard published an important study stating that household cleaning is active at night.
The researcher said in statements to the Scientific American website, which specializes in scientific research: “While waking up, the cleaning process stops. The reason for this is likely because the accuracy of the work of the neural systems necessary to process the influences of the outside world is not compatible with the washing process”.
These results confirm that the recently discovered brainwashing process is one of the most important benefits of sleep.
“When you wake up feeling energized after a period of restful sleep, it’s likely because your brain has undergone a reset. This is similar to what happens with car maintenance,” she explains.
The theory between rejection and proof
But these previous studies were conducted on mice whose minds are smaller and less complex than those of humans.
Also, her sleep periods are usually intermittent and not continuous like humans.
Therefore, many scientists rejected the theory of washing the human mind during sleep.
“10 years ago, talking about fluid flow inside the brain seemed like heresy”, says Jonathan Kipnis, a neuroimmunologist at the University of Washington School of Medicine.
Researchers have spent the past ten years studying whether brainwashing occurs in humans similarly to what happens in mice.
Research has proven the validity of this theory.
In fact, electrical waves that move inside the brain during sleep push cerebrospinal fluid inside and outside the brain.
Researchers say that the human body produces between 3 and 4 times its reserve of cerebrospinal fluid every day. It then gets rid of it. Some early studies realized that the flow of these fluids is linked to the heartbeat. However, it was not clear during previous studies what change occurs in the flow of these fluids during sleep.
Between waking up and sleeping
During the experiment conducted by researcher Niedergaard to measure the rates of elimination of amyloid proteins, the researchers injected fluorescent tracers. These were injected while mice were awake, asleep, and anesthetized. This was to monitor the flow of cerebrospinal fluids within the spaces around the blood vessels.
They found that the flow of these fluids decreased by 95% during wakefulness compared to what happens during sleep.
The volume of these channels between the vessels also expands by 60% when the mice are asleep or anesthetized.
This confirms that the body undergoes physiological changes during unconsciousness. These changes increase the brain’s ability to get rid of its waste.
In a similar human study conducted in 2021, neurosurgeon Pierre Christian Eddy of Oslo University Hospital in Norway injected fluorescent tracers. These tracers were used to monitor spinal fluid flow into a group of volunteer patients. The patients were divided into two groups.
Members of the first group were allowed to sleep normally throughout the night. Meanwhile, members of the second group were kept awake during the same period.
Members of both groups underwent MRI twice overnight and the following day.
During the experiment, it was found that the movement of fluorescent tracers used to monitor cerebrospinal fluid flow was significantly slower. This occurred in volunteers who were not allowed to sleep.
It also appeared that even after they were allowed to sleep the next night, their cerebrospinal fluid flow rate remained slow. This was compared to members of the other group.
This indicates that the onset of sleep deprivation cannot be easily compensated for by simply sleeping the next night.
Eddie stressed that “although the mechanism of action of the glymphatic system differs between humans and mice in general, as changes in the human mind occur within hours and not within minutes like mice, it is certain that the human mind also washes during sleep. Moreover, the lack of sleep actually negatively affects the mechanism of action of this system.”
