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Observations

Observations

Opinion, arguments & analyses from the editors of Scientific American

To sleep, perchance to dream--and learn

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dream nap sleep learn memory improveDreams might be helping your brain do more than express Freudian fixations or practice escapes from prehistoric predators. They are there, in part, to help you learn, according to a new study from Harvard University.


The idea that dreams can help with creative problem-solving has been discussed for decades, along with observations that sleep boosts memory. But the new research, which will be published in May in Current Biology, provides evidence that dreams really do help people retain new information—but only if it is worked into the reverie.


"After nearly 100 years of debate about the function of dreams, this study tells us that dreams are the brain's way of processing, integrating and really understanding new information," Robert Stickgold, director of the Center for Sleep and Cognition at Beth Israel Deaconess Medical Center at Harvard Medical School and senior author of the study, said in a prepared statement.


To peek into dreams' roles in learning, researchers tested 99 college students with a three-dimensional computer maze task. The subjects were instructed to do their best to navigate through the maze as quickly as possible. After about an hour, the subjects spent the next 90 minutes either taking a nap or sitting quietly (watching videos or just relaxing). The sleep subjects, who were not allowed to go into REM sleep (which has previously been linked to learning and problem solving), reported if they had dreamed and what they had dreamed about, and the awake group periodically told researchers what they were thinking about. Five hours after the first test, all the subjects were tested again.


Nappers who reported dreaming about an aspect of the task later had a 10-fold improvement on their maze-navigating abilities compared to their compatriots who did not dream about it or who remained awake.


"Dreams are a clear indication that the sleeping brain is working on memories at multiple levels, including ways that will directly improve performance," Stickgold said.


Those who dreamed about the maze, however, did not report precise representations of the task, but rather "remote associations and memories thematically related to the task," the researchers described in their paper.


"These dreamers described various scenarios—seeing people at checkpoints in a maze, being lost in a bat cave or even just hearing the background music from the computer game," Erin Wamsley, a postdoctoral researcher at Beth Israel and Harvard Medical School, said in a prepared statement. Similar associative—but not identical—patterns have been observed in brain-activation patterns of rodents sleeping after completing an activity.


One of the most interesting findings, the researchers noted, was that motivation to do well in the task appeared to have little to do with how much subjects improved. In fact, subjects in the awake group who were most motivated to solve the puzzle quickly and thought about it between tests fared no better on the second test than those who didn't care as much or didn't report dreaming about it. But those in the nap group who dreamed about the maze were among those who did most poorly on the initial task and consequently improved the most.


Wamsley suggested this might be because "if something is difficult for you, it's more meaningful to you, and the sleeping brain therefore focuses on that subject—it 'knows' you need to work on it to get better, and this seems to be where dreaming can be of most benefit."


So dream on—your memory and problem-solving abilities might just be the better for it.


Image courtesy of iStockphoto/AtnoYdur

The views expressed are those of the author and are not necessarily those of Scientific American.

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