Sleep Deprivation Stirs Up Emotions

Study Explains Why Lack of Sleep May Lead to Irrational Behavior

Medically Reviewed by Louise Chang, MD on October 22, 2007

Oct. 22, 2007 -- Sleep deprivation may make it harder to keep your emotions in check.

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 normally.

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 images.

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.

"Sleep appears to restore our emotional brain circuits, and in doing so prepares us for the next day's challenges and social interactions," says Walker.

Show Sources

SOURCES: Yoo, S. Current Biology, Oct. 23, 2007; vol 17: pp R877-R878. News release, Cell Press. News release, University of California, Berkeley.

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