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New Insights on Anxiety, Sleep Disorders

Newly Discovered Brain Protein Plays Key Role

Medically Reviewed by Brunilda Nazario, MD on August 18, 2004
From the WebMD Archives

Aug. 18, 2004 -- Millions of people are affected by anxiety and sleep disorders. Now, researchers may be one step closer to understanding -- and eventually resolving -- these complicated conditions after studying a newly discovered brain protein.

The protein is called neuropeptide S, and it "potently modulates wakefulness and could also regulate anxiety," say researchers from the University of California Irvine and the Scripps Research Institute in La Jolla, Calif.

They published their findings in the journal Neuron.

In the study, researchers find that injections of neuropeptide S in mice and rats not only increase physical activity and wakefulness, but can also decrease the duration of rapid eye movement (REM) and slow-wave sleep.

During REM sleep there are increases in brain activity and eye movement, yet muscles are relaxed. This stage of sleep is associated with intense dreaming. Slow-wave sleep is also a deep sleep stage.

"The effects of [neuropeptide S] on inducing wakefulness are rapid [during the first hour after injection] and potent, since low doses of [neuropeptide S] are sufficient to reduce all sleep stages ... suggesting a profound change in sleep architecture," write the authors.

The protein was found to be produced in parts of the brain known to regulate arousal and anxiety, in a cluster of previously unidentified cells. The protein seemed to function in areas of the brain related to stress.

The study also showed that mice that received neuropeptide-S injections showed less anxiety-associated behavior in four different stressful situations.

The discovery "might help to further our understanding of sleep disorders, such as insomnia and pathological states of anxiety," write Rainer Reinscheid, PhD, assistant adjunct pharmacology professor at the University of California Irvine, and colleagues.

"We may be at the tip of the iceberg" in understanding neuropeptide S, says Reinscheid, in a news release. Eventually, treatments for sleep and anxiety problems could result from work on the brain protein.


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SOURCES: Reinscheid, R. Neuron, Aug. 19, 2004; vol 43: pp 487-497. News release, University of California Irvine. News release, Cell Press.

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