A good night's sleep is crucial to storing knowledge learned earlier in the day — that much was known. Now, a new study finds that getting shut-eye before you learn is important, too.
Volunteers who took a 100-minute nap before launching into an evening memorization task scored an average of 20 percentage points higher on the memory test compared with people who did the memorization without snoozing first.
"It really seems to be the first evidence that we're aware of that indicates a proactive benefit of sleep," study co-author Matthew Walker, a professor of psychology and neuroscience at the University of California, Berkeley, told LiveScience.
"It's not simply enough to sleep after learning," Walker said. "It turns out you also need to sleep before learning."
Earlier research has found that dreams boost learning, with one study suggesting a 90-minute nap may help lock in long-term memories. But Walker's research, published this week in the journal Current Biology, finds that another phase of sleep, called nonrapid eye movement (NREM) is most closely linked to the learning boost provided by a nap.
Walker and his colleagues recruited 44 volunteers — 27 women and 17 men — to come to the sleep lab at noon. First, the volunteers were given a task in which they had to memorize 100 names and faces. Then they were tested for how well they recalled the face-name matches.
Next, the researchers tucked half of the volunteers in for a nap between 2 p.m. and 3:40 p.m. The scientists measured the napping volunteers' brain waves as they slept. The other group of participants stayed awake and did daily activities as they normally would. At 6 p.m., both groups memorized another set of 100 faces and names and were tested on their memory. (The experiment was set up so nappers had more than an hour to shake off any remaining fuzziness before the test, Walker said.)