A new study provides important physical evidence to support the idea that sleep helps cement and strengthen new memories. Published in the journal Science, the study shows sleep after learning causes very specific structural changes in the brain — namely growth of connections between brain cells that help them pass information to each other.

In experiments with mice, researchers showed for the first time that learning and sleep cause physical changes in the motor cortex, a brain region involved with voluntary movements.

“Here we’ve shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory,” explained Wen-Biao Gan, professor of neuroscience and physiology at NYU Langone Medical Center in New York, NY. “We also show how different types of learning form synapses on different branches of the same neurons, suggesting that learning causes very specific structural changes in the brain.”