Scientific American:

Most of us could use more sleep. We feel it in our urge for an extra cup of coffee and in a slipping cognitive grasp as a busy day grinds on. And sleep has been strongly tied to our thinking, sharpening it when we get enough and blunting it when we get too little.

What produces these effects are familiar to neuroscientists: external light and dark signals that help set our daily, or circadian, rhythms, “clock” genes that act as internal timekeepers, and neurons that signal to one another through connections called synapses. But how these factors interact to freshen a brain once we do sleep has remained enigmatic.

Findings published on October 10 in two papers in Science place synapses at center stage. These nodes of neuronal communication, researchers show, are where internal preparations for sleep and the effects of our sleep-related behaviors converge. Cellular timekeepers rhythmically prep areas around the synapses in anticipation of building synaptic proteins during slumber. But the new findings indicate neurons curtail their regular on-off cycles of building these critical proteins in the absence of sleep.

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