You really can learn while you sleep

Brain stays busy during lights-out

2012 SCIENCE NEWS TOP 25: 17

You may think of sleep as a time of repose. But scientists discovered this year that, under the right circumstances, your slumbering brain can sign on for the night shift.

New research shows that the brain may multitask during sleep, learning skills and solidifying memories. PIKSEL/istockphoto

While visiting the Land of Nod, people might improve their musical abilities (SN: 7/28/12, p. 10), learn to associate a smell with a sound (SN: 10/6/12, p. 9) or solidify negative feelings (SN: 2/25/12, p. 8). These results, and others like them, are pushing the boundaries of what scientists think the sleeping brain accomplishes.

“We want to understand where the borders lie between what we can and cannot learn during sleep,” says Anat Arzi of the Weizmann Institute of Science in Israel. This year, her team described the brain’s ability to learn to associate a particular tone with the smell of rotting fish while fast asleep. Another study found that people can also sharpen existing skills during a nap. After listening to a nap-time song, volunteers were better at hitting the right notes on a keyboard.

The science isn’t clear enough to suggest that students should, for example, play Japanese vocabulary tapes overnight, but the results do show that the sleeping brain assimilates information. And the implications go beyond cramming for a test.

Sleeping after a painful experience may lock negative memories into the brain, for instance. Staying awake during a crucial window may help lessen a trauma’s emotional impact. A study in mice accomplished the same thing without them losing sleep: A drug injected into the animals’ brains lessened a painful memory’s effect while the animals dozed (SN: 11/17/12, p. 14).

Because scientists still don’t understand why humans need to spend a big chunk of their lives asleep, some question the wisdom of giving the brain more work. Perhaps the brain ought to be left alone during the night and given time to do whatever it needs to do, says sleep researcher Robert Stickgold of Harvard Medical School. “I would argue that sleep might be smarter than you,” he says.

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Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.