Sleep plays an important role in our wellbeing. Researchers have discovered that during this important activity, brain synapses, which are the connection between neurons, are able to shrink by 20 percent of normal in order to reset and prepare for the full day ahead.
The researchers discovered that after sleep, the brain synapses begin to grow stronger again as they constantly receive new input throughout the day. This type of reset consisting in the shrinking of brain synapses is called synaptic homeostasis. It allows us to rest and forget non-essential information, which otherwise could lead the connections to become overloaded and eventually burn out. Thus, the process in important for self-preservation.
Dr. Chiara Cirelli, the co-author of the study and a researcher at the Wisconsin-Madison center for Sleep and Consciousness, stated that sleep is the optimal time where the brain synapses can reset because during the day humans tend to be active, always receiving some form of input, being stimulated and learning something new. However, during sleep our brains are not focused on the outside world as much, allowing the synapses to reset.
Cirelli initially proposed the hypothesis of synaptic homeostasis in collaboration with her colleague, Dr. Giulio Tononi, back in the year 2003. However, only now were they able to have direct visual evidence of the phenomenon, which manifests itself through the shrinking of the synapses.
For their study, they analyzed the activity of brain synapses in mice when they were asleep. The study, published in the journal Science, consisted in an intricate experiment over a period of four years. Their findings confirm the fact that sleep helps humans consolidate their memories and allows us to continue to learn.
The analysis of the mice’s brain synapses was conducted using a new type of electron microscopy. This technology is able to identify small changes in the brain’s synapses as they shrink and expand, even at the nanometer level. They found that the synapses were 18 percent smaller only after a few hours of sleep. This phenomenon occurred in around 80 percent of synapses, with the largest ones did not experience any changes.
What do you think about the changes in the brain synapses? How often and how much do you sleep during a normal day?
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