[cougarnurse]

I found this interesting:

According to researchers from the University of California (UC) Berkeley and Harvard Medical School, sleep deprivation causes elevated activity in the emotional centers of the brain most closely associated with psychiatric disorders such as depression.

"We have known for a long time that people with psychiatric disorders exhibit lack of sleep," said Matthew Walker, assistant professor of psychology at UC Berkeley.

Walker, along with research assistants at Harvard Medical School, divided 26 healthy patients ages 24 to 31 into two groups. One group was kept awake for 35 hours straight, while the other group was allowed to sleep approximately eight hours. Both groups were then put inside a magnetic resonance imaging (MRI) scanner and shown a series of 100 images with content that began relatively benign and became increasingly more disturbing.

The researchers found that in the sleep deprived group, there was a 60 percent increase in activity of the amygdala, the brain's emotional control center, when viewing negative images compared to the group that received a full night's sleep. They also noted that a lack of sleep can affect the circuit connection between the prefrontal cortex and the amygdala. The prefrontal cortex acts as a "volume control," inhibiting activity in the emotional brain.

"[We] could hypothesize that sleep deprivation can reduce levels of activity in the prefrontal cortex," said Seung-Schik Yoo, associate professor of radiology at Harvard Medical School. "Therefore, the amygdala will increase in activity."

"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," Walker said.

Walker observed that the findings could help explain road rage. "One of the functions of sleep is to reset and replenish the emotional integrity of our brain circuits so we can approach the day's emotional challenges in appropriate ways," he said. "If you don't get a good night's sleep, you'll be making irrational choices."

Walker and his team plan to conduct several more studies exploring these new findings.

The study was published in the October 22nd issue of Current Biology.

'Cat'