Summary of content
New research suggests that sleep may be related to cleaning up metabolic waste in the brain. If you sleep badly, resulting in long-term ineffective cleaning of metabolic waste, the result is likely to be Alzheimer's disease.
Damage caused by not sleeping does not seem to be permanent and can be easily recovered. Prolonged lack of sleep can be harmful to the body.
What is the main basis for cleaning up the metabolic waste generated by the brain? The answer is cerebrospinal fluid. It is a liquid as clear as "water".
Only during deep sleep does cerebrospinal fluid flow into the brain tissue to clean the brain.
If future scientists can master ways to control cerebrospinal fluid flow, They can better prevent Alzheimer's disease.
Most of the earth's terrestrial animals sleep, and humans are no exception. But why do animals have to sleep? What exactly is the function of sleep? These two questions may seem simple, but scientists still haven't found answers.
Man recovered after 11 days and 25 minutes of no sleep mental problems rested for two days
Whatever the real reason, we all know that the feeling of standing still and not sleeping is terrible, and this trick can even be used as a means of extorting confessions by torture.
In the 1960s, a high school student named Randy Gardner in San Diego, California, decided to challenge her life to see how long she could stay asleep. In the end, he remained awake for 11 days and 25 minutes under the supervision of several scientists, setting a world record for the longest time without sleep.
It is said that in the last few days, he had serious mental problems, which were manifested as cognitive impairment, emotional loss of control, short-term memory loss, etc., and even hallucinations, like drug use.
However, after finishing the test, he fully recovered after two days of rest, and there seems to be no sequelae left after that. This shows that the damage caused by not sleeping does not seem to be permanent and can be easily recovered.
Deep sleep
Remove metabolic waste products produced by brain nerve cells
According to this line of thinking, some people have proposed a hypothesis that the main role of sleep is to remove metabolic waste products produced by brain nerve cells. Of course, too much waste accumulation is not good, but if the accumulation time is not long, as long as it is cleaned up by making up for sleep, it can be completely restored to its original state. So a person occasionally staying up late is not a big problem, only a long period of lack of sleep will be harmful to the body.
So, what is the main basis for cleaning up the metabolic waste generated by the brain? The answer is Cerebrospinal Fluid. It's a clear liquid like water that flows freely between brain tissue and spinal cord, and it functions a bit like a cleansing fluid that can be used to clean up waste produced by nerve cells through repeated rinsing.
In 2013, someone did an experiment and found that the brain nerve cells of mice would shrink in size during sleep, and the vacant places would be quickly filled by cerebrospinal fluid, and scientists speculated that mice used this method to flush brain tissue. But this process can only happen during sleep, and maybe that's what sleep really means.
However, human brain cells do not shrink in size during sleep, how does cerebrospinal fluid rush into the brain to start "working"?
Dr. Laura Lewis of Boston University in the United States suspects that the flow of cerebrospinal fluid in humans is related to brain waves during sleep, and the two sides are likely to be synchronized. As we all know, human sleep is divided into two stages: rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM), the former is marked by rapid eye rotation, usually accompanied by the appearance of dreams. The latter can be simply understood as deep sleep, when the firing patterns of brain neurons tend to be consistent, either everyone is discharged together or collectively hibernates at the same time. At this time, the frequency of brain waves will slow down, so it is also called "slow wave sleep" by scientists.
To study the relationship between cerebrospinal fluid and brain waves, Dr. Lewis designed a non-invasive brain nerve experiment. The researchers recruited 13 volunteers to sleep in an electrical resonance imaging machine (MRI) wearing an EEG Cap , which can measure what stage of sleep the volunteers are in , and the latter to measure the blood oxygen consumption in the volunteers' brains and the flow of cerebrospinal fluid.
The experimental results clearly show that the flow of cerebrospinal fluid in humans is closely related to the state of sleep. Whenever the volunteers fell into deep sleep, cerebrospinal fluid would pour into the brain tissue in large quantities and begin to clean up.
cerebrospinal fluid
Brain cleaning
Why does CSF flow into brain tissue only during deep sleep? Dr. Louis thinks it makes sense.
It turns out that the cranial nerves need to consume a lot of oxygen when working, which is brought in by the blood, and when people are awake (and when they are rem sleeping), the cranial nerves have been continuously discharging, and the oxygen consumption remains high, so the blood must remain high-speed and fill the entire brain tissue, only in this way can the oxygen supply of the brain nerve be guaranteed. But in the deep sleep stage, when the brain nerves are collectively dormant, the oxygen consumption drops rapidly, not so much blood is needed, at this time the blood flow rate in the brain will be reduced by about 25%, and the vacated part is filled by cerebrospinal fluid, so scientists observed that the volunteers' blood and cerebrospinal fluid alternately enter the brain, rotating every 20 seconds.
In other words, the human brain slows down the frequency of brain nerve firing during deep sleep, thereby reducing dependence on blood, and cerebrospinal fluid can take the opportunity to enter the brain and begin to clean up, and sleep is in this way to clean the brain.
Prevention of Alzheimer's disease
Sleep well, don't stay up late
So, what waste does the brain need to clean up every day? The answer is likely to include β-amyloid (β-Amyloid).
Anyone familiar with Alzheimer's disease knows that this protein has always been the most important pathological indicator of the disease, and was even once considered the only cause of the disease. However, the previous development of new drugs specifically for this protein has been wiped out, indicating that there is likely to be another reason for the disease, such as other metabolic wastes related to the disease, which is why it is useless to reduce the β- amyloid, and all metabolic waste related to Alzheimer's disease must be cleaned up.
Dr. Louis's research is relevant to this. She wrote the findings into a paper published in the November 1, 2019 issue of the journal Science. She believes that if future scientists can master the method of controlling the flow of cerebrospinal fluid, they can mobilize the body's own cleaners to clean up all the waste generated by the brain, so as to better prevent Alzheimer's disease.
Before this day comes, we can also save ourselves, the way is to sleep well, don't stay up late.
1 End
1
Source: Public Health Magazine WeChat public account
Text: Yuan Yue
Editor: Li Jun
Proofreading: Yu Yunxi