Narcolepsy Patients More Likely to Have REM Without Atonia

Both narcoleptic and idiopathic sleep disorder patients may have neurobiological defects in motor inhibition

FRIDAY, July 13 (HealthDay News) -- Narcolepsy patients are more likely to have REM sleep without atonia than controls, and tend to have sleep motor abnormalities similar to patients with idiopathic REM sleep behavior disorder. Patients with the conditions may have neurobiological defects in motor inhibition, according to a report in the July issue of Sleep.

Yves Dauvilliers, M.D., Ph.D., of the Universite de Montpellier in Montpellier, France, and colleagues conducted a one-night sleep laboratory study of 16 narcolepsy patients, 16 patients with idiopathic REM sleep behavior disorder (RBD), defined as agitated motor behavior during sleep for at least six months, and 16 control subjects. Narcolepsy patients were also tested during five naps two hours apart the following day.

The researchers found that narcolepsy patients had a higher percentage of REM sleep without atonia than the control group and showed no obvious signs of abnormal motor behaviors. RBD patients showed a similar pattern of behavior, but had increased periodic leg movements during sleep as well as a higher percentage of phasic motor activity during REM sleep.

"In summary, this study shows that patients with narcolepsy have a high frequency of REM sleep without atonia and of elevated phasic EMG density in REM sleep compared with controls," the authors write. "This study also shows several REM sleep motor dyscontrol similarities between narcolepsy and RBD, suggesting the possibility of a common neurobiological defect of motor inhibition during REM sleep."

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