Scientific findings point out that in relation to the brain sleep also has a physiological function. Namely an influence on the physical and bio-chemical procedures in the brain cells as well as in the brain tissue. Via the lymphatic system the body transports harmful and toxic substances (toxins) out of the cells and out of the circulatory system of our body to the excretory organs. It has similar tasks like our blood system: removal of proteins, bacteria, toxins and purification of the lymphatic fluid in our lymph nodes. Astonishingly, our central nervous system including our brain is not connected to this lymphatic network. So far, it was assumed that our brain is processing and neutralizing the existing toxins by itself on cellular level. But, when getting older and as soon as this process fails, symptoms of decline arise due to accumulation of toxins and creation of plaque.
Brain possesses own detoxification system
Scientific tests with mice brought more clarity into this process. Now the theory arose that there might exist an own detoxification system for our brain, similar to the lymphatic system. In this study, this system is called “glymphatic system” and refers to the so-called “glial cells” which play a decisive role. Dr. Rudolf Virchow discovered these glial cells. Already in his lifetime, he assumed that the glial cells are having supporting- and holding functions for the neural cells and therefore called them “glial cells”, deriving from the Greek word “glia” (glue). Nowadays it is known, that glial cells actually serve as supporting cells for the mechanical stabilization of the neural cells by taking over the tasks of the connective tissue in the nervous system, amongst others. Now, experiments with mice gave an insight into the mechanism of this and for the brain important glymph system. With special microscopes and coloring technologies the group of scientists was able to confirm this until then only suspected mechanism. For this purpose luminous isotopes were injected into the mice. Subsequently the scientists followed their path through the brain. Here, the found out that during sleeping mice-brains were busy with disposal of waste products from the previous day!
Crucial factor: sufficient sleep!
While the mice were asleep the brain liquids (liquor) circulated significantly faster. Consequently, sleep has a purifying effect onto the brain and on toxic metabolic products. During sleep, they clearly can be removed quicker than during waking state. The scientists were able to clarify the backgrounds, too: while the mice were sleeping, the space between the brain cells widened by 60 %. As a result, more “open spaces” arise and more brain liquid can flow through the brain tissue. In comparison with mice awake the flow velocity is much higher. Out of this reason scientists assume that the cellular structure of the brain is changing during sleep. This enables to quicker rinse out toxic and harmful metabolic products.
To be completely sure, scientist Maiken Nedergaard has repeated the experiment with sleeping mice. Here, two colors were added to the liquor. The presence of these colors in the brain was measured with two-photons-fluorescence. Like in the previous experiments the intercellular space clearly enlarged during sleep. Their share of the overall volume rose from 15 % by more than its half to 23 %. And exactly here a clear rise of the brain liquid happens. At the same time a flow through the brain tissue up to tiniest brain regions is taking place. Something, that according to Nedergaard only is possible during sleep. Consequence of these sleep depending process is an increased flushing out of beta-amyloids, which are main cause for arising of dementia and especially for Alzheimer’s. Here, scientist Maiken Nedergaard also might have found a further answer why we human beings need 7-9 hours of sleep every night: to purify and free our brain from toxic substances like beta-amyloids!
Image Source: ©fotolia