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2008-05-21 08:31:34
By Julie SteenhuysenTue May 20, 6:53 PM ET
Being deprived of sleep even for one night makes the brain unstable and prone
to sudden shutdowns akin to a power failure -- brief lapses that hover between
sleep and wakefulness, researchers said on Tuesday.
"It's as though it is both asleep and awake and they are switching between each
other very rapidly," said David Dinges of the University of Pennsylvania School
of Medicine, whose study appears in the Journal of Neuroscience.
"Imagine you are sitting in a room watching a movie with the lights on. In a
stable brain, the lights stay on all the time. In a sleepy brain, the lights
suddenly go off," Dinges said in a telephone interview.
The findings suggest that people who are sleep-deprived alternate between
periods of near-normal brain function and dramatic lapses in attention and
visual processing.
"This involves more structures changing than we've ever seen before, but
changing just during these lapses," Dinges said.
He and colleagues did brain imaging studies on 24 adults who performed simple
tasks involving visual attention when they were well rested and when they had
missed a night's sleep.
The researchers used a type of brain imaging known as functional magnetic
resonance imaging, or fMRI, which measures blood flow in the brain.
They found significant, momentary lapses in several areas of the brain, which
seemed to frequently falter when the people were deprived of sleep, but not
when these same people were well rested.
"These people are not lying in bed. They are sitting up doing a task they
learned and they are working very hard at doing their best," Dinges said.
He said the lapses seem to suggest that loss of sleep renders the brain
incapable of fully fending off the involuntary drive to sleep.
He said the study makes it clear how dangerous sleep deprivation can be while
driving on the highway, when even a four-second lapse could lead to a major
accident.
"These are not just academic interests," he said.
(Editing by Will Dunham and Cynthia Osterman)