The team of researchers, who first published their findings in this month's Journal of Neuroscience, found that sleep increases the production of cells in the brain--specifically oligodendrocytes, which create myelin. This hike is myelin is vital to brain function and repair, as myelin acts as an insulator and “protects our brain’s circuitry,” reports BBC.
Studying the sleep habits of mice, the researchers found that the boost in the production of oligodendrocytes was greatest when mice were in REM sleep--deep sleep most associated with dreaming.
However, the researchers found that when the mice were forced to stay awake, genes associated with stress and cell death were turned on.
“For a long time, sleep researchers focused on how the activity of nerve cells differed when animals are awake versus when they are asleep,” Dr. Cirelli, a researcher on the team told BBC. “Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake.”
So long story short: sleep.