We’ve all been there: After struggling over a problem for hours, we rest our eyes for a few minutes and suddenly the answer is lying before us, clear as day.
This common phenomenon has contributed to the idea of the so-called power nap, a quick snatch of rest that stops short of deep sleep yet somehow manages to refresh and stimulate. Although there is much about the power nap that remains a mystery, researchers have begun to uncover the brain processes behind the little miracles it produces.
The latest research, presented today at an annual meeting of neuroscientists, may help explain the mental spark that sometimes occurs during a nap. Researchers monitoring the brain activity of 15 at-rest individuals found that the right side of their brain—the hemisphere most associated with creativity—chattered busily to itself as well as to the left hemisphere, which remained relatively quiet.
“The right side of the brain was better integrated,” says study author Andrei Medvedev, Ph.D., an assistant professor at Georgetown University’s Center for Functional and Molecular Imaging, in Washington, D.C.
Medvedev had expected the left side of the brain to be better integrated, since that hemisphere tends to be dominant in right-handed people (and vice versa in left-handed people). All but two of the study participants—and fully 95% of the general population—are right-handed.
The division of labor between the right and left sides of the brain isn’t as clear-cut as once thought. Generally, though, the right hemisphere is associated with creative tasks, such as visualization and big-picture thinking, while the left is more analytic, specializing in numbers and language processing.
It’s not yet clear how, or if, the new study results fit into this framework. But Medvedev speculates that the right brain may be performing important “housecleaning” tasks during a nap. The most important of these is probably the consolidation of memories, although other tasks are probably involved as well, he says.
This hypothesis jibes with the current understanding of the essential role that sleep plays in memory formation, says Suresh Kotagal, M.D., a professor of neurology at the Mayo Clinic in Rochester, Minnesota.
“We are exposed to certain pieces of information, but if we get to sleep on it, the sleep seems to facilitate the transfer of information from the short-term memory bank into the more permanent memory bank,” says Kotagal, who was not involved in the study.
Jonathan Friedman, M.D., director of the Texas Brain and Spine Institute, in Bryan, says the new findings come at a time of growing interest in the neuroscience of sleep.
“Emerging scientific evidence suggests that naps—even very short ones—significantly enhance cognitive function,” Friedman says. “Increasing understanding of how sleep improves brain function may someday allow us to harness this effect, and the current study may open one of many doors in this regard.”
Medvedev and his colleagues used a type of brain imaging known as near-infrared spectroscopy, which involves placing optical fibers similar to electrodes symmetrically around a person’s scalp. These “optodes” send infrared light through the brain and measure how much light returns.
The intensity of light bouncing back provides an estimate of the blood flow in different regions of the brain. Blood flow, in turn, is an indicator of how active those regions are.
The study results, which Medvedev presented at the Neuroscience 2012 meeting in New Orleans, should be considered preliminary. They haven’t been peer-reviewed by other experts in the field, and they’ll need to be replicated in other studies before firm conclusions can be drawn.
But they do shine a light—infrared light, in this case—on how the two sides of our brain interact when we’re at rest. “This may change our perspective of the brain,” Medvedev says. “We may just conclude that the sub-dominant part of the brain may also be important.”