TUESDAY, March 8 (HealthDay News) -- Your brain's ability to
learn may get recharged during the light, dreamless slumber that
accounts for up to half of your night's sleep, according to a new
Researchers at the University of California, Berkeley conducted
tests on 44 healthy young adults and found strong evidence that
bursts of brain waves called sleep spindles may network between
important regions of the brain to clear a path to learning.
These spindles -- which are fast pulses of electricity that are
generated during non-rapid eye movement (REM) sleep and can occur
up to 1,000 times per night -- help to transfer fact-based memories
from the brain's hippocampus to the prefrontal cortex's "hard
This enables the hippocampus, which has limited storage space,
to take in fresh data, the researchers explained.
"All these pieces of the puzzle tell a consistent and compelling story -- that sleep spindles predict learning refinement," senior author Matthew Walker, an associate professor of psychology and neuroscience, said in a UC Berkeley news release.
Spindle-driven networking is most likely to occur during stage 2
of non-REM sleep, which occurs before the deepest non-REM sleep and
dream-inducing REM sleep. Stage 2 non-REM sleep can account for
half of a person's sleep.
"A lot of that spindle-rich sleep is occurring in the second half of the night, so if you sleep six hours or less, you are shortchanging yourself. You will have fewer spindles and you might not be able to learn as much," lead author Bryce Mander, a post-doctoral fellow in psychology, said in the news release.
In this study, the researchers subjected 44 healthy young adults
to a demanding memorizing task. All participants did equally well.
The researchers then divided the group in two, with one half taking
an hour and a half nap while the other half stayed awake.
That evening, the entire group was given another round of
memorizing tasks. This time, though, those who had remained awake
throughout the day had more trouble memorizing the new information.
In contrast, those who had napped performed better than the waking
group. In addition, the nappers appeared to actually have an
improved capability for learning, the study found.
The study team then turned to electroencephalogram tests, which
measured electrical activity in the brains of the nappers. These
showed that the more sleep spindles the nappers produced, the more
refreshed they appeared for learning. In addition, researchers
discovered that sleep spindles were linked to brain activity
looping between the lobes of the brain that house the hippocampus
and prefrontal cortex -- both critical areas for memory.
The study appears Mar. 8 in the journal
The U.S. National Institute of Neurological Disorders and Stroke
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