April 22, 2010 -- Napping after working on a difficult task may make the job easier to do upon awakening, according to a new study.
The research, reported in the April 22 issue of Current Biology, offers evidence that napping might be a good strategy for studying.
Researchers asked 99 participants to sit in front of a computer screen and try to learn the layout of a three-dimensional maze so that they could find their way to a landmark, in this case, a tree, five hours later when placed at a random spot within the virtual space.
Study participants who were allowed to take a nap and also dreamed about the task showed more improvement in performance in a retest than those who did not nap or those who napped but did not report dreaming about the maze.
In some cases, people who dreamed simply remembered music associated with the computer maze.
One participant reported dreams of seeing people at various spots in the maze, even though the maze they saw before napping had no virtual people or checkpoints.
Another reported dreaming of negotiating bat caves, thinking the caves were like mazes.
Dreams Linked to Memory
“We think that the dreams are a marker that the brain is working on the same problem at many levels,” researcher Robert Stickgold, PhD, director of the Center for Sleep and Cognition at Harvard Medical School, says in a news release. “The dreams might reflect the brain’s attempt to find associations for the memories that could make them more useful in the future.”
He says that at first researchers “thought that dreaming must reflect the memory process that’s improving performance” but the content of reported dreams led to different conclusions.
Apparently, the researchers say, it’s not that the dreams led to better memory, but that dreaming may be a sign that other, unconscious parts of the brain are working hard to remember how to get through the maze during the dream state.
In essence, the dreams are a side effect of the memory process, the study authors write.
Stickgold says there may be ways to take advantage of this phenomenon for improving memory and for learning.
He speculates that it may be better to study hard just before going to sleep, rather than in the afternoon, or to take a nap after a period of intense study.
He says that, in general, people sometimes take note of their study habits or mental processes while awake, and that this causes them to dream about something they need to remember.
Why Do We Dream?
It’s possible, the researchers say, that finding more directed ways to guide dreams could prove useful, to make the brain work on specific things while asleep.
Stickgold says the study may shed light on the deeper questions of why people dream and help pinpoint the function of dreaming.
“Some have viewed dreaming as entertainment, but this study suggests it is a by-product of memory processing,” he says in the news release.
He says he suspects that it’s not necessary for people to remember dreams to gain some benefit.
“Subjects who napped following training improved significantly more at retest than those who remained awake,” the authors write.
Sleeping didn’t allow participants to recall exactly what they had seen, but produced memories related to the virtual environments they’d viewed, the authors write.
They write that memory may be enhanced through processes that “slowly integrate critical elements of a recent experience” into the brain’s memory networks.