A study has molecular and structural evidence of that woolly feeling — proteins that build up in the brains of sleep-deprived fruit flies and drop to lower levels in the brains of the well-rested. The proteins are located in the synapses, those specialized parts of neurons that allow brain cells to communicate with other neurons.Sleep researchers believe it is more evidence for their theory of "synaptic homeostasis." This is the idea that synapses grow stronger when we're awake as we learn and adapt to an ever-changing the environment, that sleep refreshes the brain by bringing synapses back to a lower level of strength. This is important because larger synapses consume a lot of energy, occupy more space and require more supplies, including the proteins examined in this study.
Sleep — by allowing synaptic downscaling — saves energy, space and material, and clears away unnecessary "noise" from the previous day, the researchers believe. The fresh brain is then ready to learn again in the morning.
On the left, the brain of the well-rested blue fly has low levels of a synaptic protein called BRP in this 3D view from a confocal mircoscope. On the right, the brain of the sleep-deprived fly glows orange in areas of BRP concentration. In the tired fly, the protein is present at high concentartions in three major areas of the fly's brain that are associated with learning. Sleep reduces the levels of this protein, an indication that synapses get smaller and/or weaker. This process of "downscaling" may be important so the brain is reset to normal levels of synaptic activity and can begin learning again the next day.



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