By finding ways to interfere with that unconventional wiring, scientists may advance on new treatments for insomnia, the researchers said. Natural variation in this brain system might also explain differences among people in their susceptibility to sleep disturbances.
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.
Scientists discovered hypocretin neurons while studying narcolepsy, a condition marked by sudden bouts of deep sleep. Narcolepsy generally stems from a shortage or malfunction of hypocretin neurons. The neurons also induce appetite, an important activity for the control of food intake. Yet the integration of the
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