BEACON TRANSCRIPT – Everybody wonders what is the purpose of sleep. Is it to regain the energy lost during the day and clean the brain? Is it to stay safe from the harmful external factors? New studies found that the real purpose of sleep might actually be to forget.
People sleep to forget what they have learnt during the day. The process of learning creates neural connections that allow neurons to send signals to each other. The place of the new memories is in these connections.
A proposal made by University of Wisconsin-Madison biologists Giulio Tononi and Chiara Cirelli suggested that these neural connections were so intense during the day that they grow “noisy” at some point. Therefore, when humans sleep, they reduce some of these synapses to calm the noise.
They called this theory the synaptic homeostasis hypothesis. Without this homeostasis, synapses could burn out exactly like an overloaded electric circuit. They had found some indirect evidence in support of this hypothesis.
Now, they have the direct evidence they needed. They discovered a four-year experiment that showed how synapses in mice shrunk during sleep. Thus, sleep helps with the cleaning and rearrangement of synapses so that we can learn new things and keep new memories.
A team of scientists from Johns Hopkins University developed a new study where they looked at proteins in mouse brains. They observed that sleep is indeed beneficent for those cells that are responsible with memories and learning and, during sleep, animals can build up what they have learnt and then use the information as soon as they wake up.
They looked at the hippocampus and cortex inside the mouse brains and analyzed the proteins in both sleeping and awake mice. The proteins in sleeping mice had a 20 percent decrease in receptor levels. Thus, mice and presumably humans, too, can only store an exact quantity of memories before the synapses need to be recalibrated. Without recalibration, the synapses may overload and cause the loss of memories.
However, do not think that synapses “forget” everything during sleep. They keep only the most important memories which need to be encoded and prevent the overload of information. This selective forgetting that occurs during sleep is one of the many mysteries of the brain that humans are still seeking to explain.
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