Monday, December 24, 2007

Unconventional Brain Circuits Offer Clues To Insomnia-obesity Connection

Unconventional Brain Circuits Offer Clues To Insomnia-obesity Connection:

Unconventional wiring of the brain circuits that govern sleep and waking might explain the prevalence of insomnia and the condition's association with obesity, according to new work published in the April issue of Cell Metabolism. Characterized by a chronic inability to fall asleep or remain sleeping, insomnia is estimated to affect one in every eight Americans.

The researchers found that so-called hypocretin neurons--having important roles in both arousal and appetite--lack the ability of most neurons to filter "noise" from signal, reported Tamas Horvath and Xiao-Bing Gao of Yale University School of Medicine. The neurons also rapidly reorganize themselves, becoming even more excitable, in response to stresses such as food deprivation, they found.

"The cell bodies of most neurons act as a filter," sorting through a multitude of signals to eliminate noise and generate an appropriate response, Horvath said. "In contrast, it appears that the basic wiring of hypocretin neurons allows noise to become the major signal."

As obesity has reached epidemic proportions, the incidence of insomnia and sleep deprivation has also risen. Studies of this apparent insomnia-obesity association have suggested a causal link between the two, but the underlying mechanism has remained unclear. The new findings of hypocretin neurons offer some possible clues, Horvath said.

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