EEGs, electrodes that record brain activity, suggest how that happened. The number of bursts of electrical activity called sleep spindles—Walker calls them “champagne pops in the brain”—that people experienced during their naps predicted how much their ability to learn would improve once they awoke. Sleep spindles, he suspects, indicate activity in the hippocampus that moves information from that region into the cortex for permanent storage. It’s like moving data from a USB stick onto a hard drive, which “both consolidates into long-term storage the information you offload and leaves you a renewed capacity for absorbing new information—learning,” says Walker. The better we move information from the hippocampus (working memory) into the cortex, the more information we can access when we need it.
Even without the midday nap, the brain has a way of carving out its own downtime, characterized by what’s called the “default-mode network”—basically, brain activity that takes place when you’re daydreaming or keeping your mind blank. Using functional MRI, scientists at Japan’s Tohoku University measured cerebral blood flow in 63 volunteers asked to keep their minds blank. Those with the greatest blood flow in the white matter that connects one neuron to another scored highest on a task requiring them to quickly generate novel ideas, the researchers reported in the journal PLoS One in November. Creativity arises from seeing connections others miss, so it makes sense that increasing the activity in white matter by letting the brain rest in default mode supports creativity. So put away the BlackBerry and let your brain idle.