A new study shows that sleep deprivation is linked to a disconnect in the
part of the brain responsible for keeping emotions under control, adding to the
already long list of negative effects of lack of sleep on health.
Researchers say the results are the first to explain on a scientific level
how lack of sleep may lead to emotionally irrational behavior.
"It's almost as though, without sleep, the brain had reverted back to
more primitive patterns of activity, in that it was unable to put emotional
experiences into context and produce controlled, appropriate responses,"
says researcher Matthew Walker, director of the University of California,
Berkeley's Sleep and Neuroimaging Laboratory, in a news release.
"You can see it in the reaction of a military combatant soldier dealing
with a civilian, a tired mother to a meddlesome toddler, the medical resident
to a pushy patient. It's these everyday scenarios that tell us people don't get
enough sleep," says Walker.
(What are you like when you go without sleep? Tell us about it on WebMD's
Sleep Disorders: Michael Breus, PhD, ABSM, message board .)
Lack of Sleep Affects Emotions
In the study, published in Current Biology, researchers examined the
effects of lack of sleep on 26 healthy adults. Half were assigned to a sleep
deprivation group and were kept awake for 35 hours, and the other half slept
The participants' brains were then scanned using functional magnetic
resonance imaging (fMRI) while they looked at 100 different images, ranging
from emotionally neutral to negative, such as mutilated bodies and other gory
The results showed that the sleep-deprived group had a much bigger reaction
to the emotionally charged images. The brain scans showed that the amygdala,
the area of the brain critical to processing emotions, appeared to overreact to
the gory images in the sleep-deprived group compared with the normal activity
found in the normal-sleep group.
"The size of the increase truly surprised us," says Walker. "The
emotional centers of the brain were over 60% more reactive under conditions of
sleep deprivation than in subjects who had obtained a normal night of
"Sleep appears to restore our emotional brain circuits, and in doing so
prepares us for the next day's challenges and social interactions," says
By Jennifer Warner
Reviewed by Louise Chang
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