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Researchers have found that when in deep sleep, the brain waves can start off a cleaning system within the brain that can protect it against Alzheimer’s and other neurodegenerative brain diseases. Researchers explained that there are several forms of brain waves especially slow ones that appear during the sleep and have been recorded using EEG (Electroencephalogram). The authors wrote, “Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain.” The new study reveals that before each of such slow waves occur in the sleeping brain there is a pulse of CSF that washes all over the brain to remove the toxins from it. This means that approximately every 20 seconds or so, the brain gets a wash down. CSF normally is the fluid flowing around the brain and spinal cord. This study reveals the link between sleep deprivation and neurodegenerative disorders such as Alzheimer’s disease. Some disruption to the way sleep is working could potentially be contributing to the decline in brain health. Researchers believe that these findings point to the fact that individuals can reduce their risk of getting Alzheimer’s disease by getting good quality sleep each night. Experts have said that people with Alzheimer’s tend to get poor sleep. Now this study links the two conditions. Another important finding from this study was that before the CSF washed the brain there was a brain wave –an electrical wave that covered whole of the brain. Before each wave of fluid, we would actually see a wave of electrical activity in the neurons. This electrical wave always happens first, and the CSF wave always seems to follow seconds later. They noted that it was the electrical wave that triggered the CSF flow. The wave was the slow brain wave that is seen in the NREM (non rapid eye movement) stage of sleep or deep stage. During non–rapid eye movement sleep, low-frequency oscillations in neural activity support memory consolidation and neuronal computation. It’s already known that people with Alzheimer's disease have less of these electrophysiological slow waves, so they have smaller and fewer slow waves. Now it is known that less of these waves also means less washing out of the toxins. It would make sense that if there’s large waves of fluid, of CSF, that that might in turn cause mixing and dispersion with other fluids in the brain and help with this waste removal process. Another finding revealed that CSF flow rose with the decrease in blood flow. They noted that lower blood flow allowed the CSF to clear out the brain better and would allow removal of toxins better. The team wrote, “Slow oscillatory neuronal activity thus leads to oscillations in blood volume, drawing cerebrospinal fluid into and out of the brain.” The authors concluded, “These results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and these CSF dynamics are interlinked with neural and hemodynamic rhythms.” Source: https://www.news-medical.net/news/20191031/Sleep-protects-the-brain-against-Alzheimere28099s-by-washing-it.aspx