Lack of sleep causes brain destruction

Many people think that little sleep has no major consequences, beyond that it causes a feeling of tiredness which can be quite bearable for some people. however, lack of sleep leads to changes in brain function which are not always easy to detect but are associated with serious long term problems.

A recent study carried out at the Polytechnic University of Marche, Italy, provides relevant information on this fact. According to the authors, little sleep can cause a substance called glia ‘eats’ healthy neural connections (The so-called “synapses”), affecting neural connectivity and increasing the risk of developing neurological disorders such as dementia. The glia is made up of cells in the nervous system called glial cells which are usually responsible for everything working as it should, but certain alterations seem to alter their behavior.

    Glial cells: astrocytes and microglia

    In order to understand the results of this research, it is necessary to be clear about the functions of glial cells in the nervous system. The study focuses specifically on the role of two of them: astrocytes and microglia.

    Glial cells or neuroglia they specialize in supporting neurons, Which are very efficient in neuronal transmission but very limited in other directions. Different types of glia provide strong structure to neurons, speed up synaptic connections, and maintain balance in the extracellular environment of the nervous system.

    Astrocytes are a type of glia located in the central nervous system, that is, in the brain and spinal cord. In addition to being part of the blood-brain barrier that nourishes and protects neurons, astroglia eliminates unnecessary synapses to promote regeneration of damaged tissue.

    Microglial or microglial cells are also located in the central nervous system. They are considered part of the immune system for their ability to phagocytize (“eat”) waste and damaged cells, which is very important in protecting the body against pathogens, infections and other threats.

    The study of Bellesi and his collaborators

    The research team of the Polytechnic University of Marche, led by Michele Bellesi, studied the effects of sleep deprivation in mice compare the brains of three sets of experimental subjects using three-dimensional measurement and representation techniques.

    Rodents from one of the groups were able to sleep freely. Those in the second were kept awake for 8 hours when they needed to sleep, while those in the third were sleep deprived for a period of 5 days. The latter group aimed to simulate chronic sleep deprivation.

    The study focused on analyzing the differences in glial cell activity according to the degree of sleep deprivation, particularly that of astrocytes and microglia, which Bellesi’s team and other research groups had previously linked to brain degeneration.

    The researchers found that the intensity of phagocytosis increased with that of sleep deficit. Thus, while astrocytes were active in 6% of the synapses of sleeping mice, they were active in 7% of low-deprivation mice and 13.5% in the chronic sleep deprivation group.

    On the other hand, Bellesi and his collaborators also identified an increase in the activity of the microglia. This may be even more relevant than the phagocytosis carried out by astrocytes, since the excess in the function of the microglia is linked to the development of neurodegenerative diseases, As we will explain later.

      Context of this research

      Previously, Bellesi’s team had found that the genes that drive astrocytes to initiate the phagocytosis process are expressed more intensely under conditions of sleep deprivation. However, until now they had not been able to prove it. direct link between the activity of this glial cell and lack of sleep.

      Studies had also been published, both with rodents and humans, suggesting a cause and effect relationship between poor sleep and increased inflammation of the nervous system. The research of the Bellesi team brings the important fact that this inflammation is due to an increase in the activity of the microglia.

      This type of glia has received a lot of attention from the scientific community due to the role of chronic inflammation in various neurodegenerative diseases, especially Alzheimer’s and Parkinson’s. The functions of microglia they become destructive rather than regenerative when the amount of brain damage is excessive.

      Implications of the results

      In summary, the results of this study suggest that the activity of certain glial cells intensifies under conditions of sleep deprivation. These data are in turn related to the known fact that if astrocytes or microglia act in excess they can cause long-term brain damage.

      In the case of astrocytes, Bellesi’s team found that lack of sleep could cause them to swallow portions of healthy synapses in addition to irrelevant connections and waste. This leads to a worsening of neuronal transmission which would become more marked as the sleep deficit is maintained.

      Excessive microglial activity has been linked to neurodegenerative diseases such as Alzheimer’s dementia. This appears to be due to the fact that the inflammatory responses elicited by this glial cell predispose to the development of major lesions if maintained for too long.

        Bibliographical references:

        • Bellesi, M .; of life, L .; Chini, M .; Gilli, F .; Tononi, G. and Cirelli, C. (2017). Sleep loss promotes astrocytic phagocytosis and microglial activation in the mouse cerebral cortex. Journal of Neuroscience, 37 (21): 5263-73.

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