During sleep, the brain is cleared of toxins accumulated as a result of mental processes during the day. U.S. scientists believe that this mechanism is one of the main causes for sleep, as reported by BBC.
The study experts found out that brain cells are reduced during sleep for easy cleaning of the whole brain. It also turned out that a failed clearance of some proteins may cause brain disorders. The question that has long worried scientists is why animals sleep, knowing that this makes them more vulnerable to predators.
It has long been known that sleep plays an important role in the formation of memories and information processing. However, the staff of the medical center at the University of Rochester believe that one of the main functions of sleep is to purify the brain. Maiken Nedergaard, the author of the study, claims the brain has a limited amount of energy, and it has “to choose” between two different functional states – wakefulness or sleep, when cleaning occurs.
The conclusion is based on the lymphatic system that the scientists revealed last year; its function in the brain is the removal of harmful substances. They watched the brain of mice and found the system to be 10 times more active during sleep. Brain glial cells that surround and support neurons shrink during sleep. This increases the size of the interstitial space (the space between cells), allowing the inflow of fluid wash toxins from the brain.
According to M. Nedergaard, this mechanism is important for the functioning of the brain, but it is not valid for the period of wakefulness. The brain spends a lot of energy for pumping fluid through their tissue, and this is probably not compatible with processing information. The authors said that the real significance of these results will be clear only after tests on humans, and it is not so difficult with MRI.
The results of the study are published in the Science journal.