Sleep clears the brain

A relatively recent study was published, which suggests that sleep can literally clear the brain.

“There is a limited amount of energy at the disposal of the brain and it seems that it has to choose between two different functional states - wakefulness and awareness or sleep and purification,” said the author of the research Maiken Nedergaard, co-director of the Medical Center at the University of Rochester. “You can imagine it as a guest reception at home. You either have fun with them or clean the room. You cannot do one thing at the same time. ”

It seems that cells are reduced during sleep by as much as 60 percent, according to the study published in the journal Science. Therefore, for cerebrospinal fluid flowing through the brain tissue, the function of which is to inject “waste” into the circulatory system, more space is released. This system of excretion of decay products is called "glymphatic system". It plays an important role in understanding neurological disorders such as Alzheimer's, as it clears the brain of toxins that may be associated with this disease.

In experiments on mice, researchers found that the glymphatic system was almost 10 times more active during sleep. This explains why, in a dream, the brain spends almost as much energy as it did during waking hours, the researchers report.

Scientists also found that the hormone norepinephrine is less active when we sleep. They suspect that it is a neurotransmitter that causes the brain to respond in response to stimuli such as fear, can control the contraction and expansion of brain cells during sleep and wake cycles.

“These results are important for the treatment of, for example, Alzheimer's disease and other brain-related disorders,” Nedergaard said. “Understanding how and when the brain activates the glymphatic system and removes “waste” is the most important first step in efforts to potentially modulate this system and encourage it to work more efficiently.”