October 10, 2019
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 don’t end up building these critical proteins in the absence of sleep.
The results suggest the brain is “getting prepared for an event, but it doesn’t mean you actually follow through on doing it,” says Robert Greene, a neuroscientist at the University of Texas Southwestern Medical Center, who was not involved in the study. Greene calls the studies “fascinating,” saying they confirm a “long suspected” connection between internal timekeeping and sleep behaviors.
When we become sleepy, two factors are in play: “sleep pressure,” or the growing allure of a beckoning pillow as waking time lengthens, and our internal clock sounding the signal that the usual point for shut-eye has arrived … Read more.