| Summary: | <i>Aralia continentalis</i> exhibits various biological activities; however, their sleep-promoting effects have not been previously reported. In this study, we evaluated the hypnotic effects and sleep–wake profiles of <i>A. continentalis</i> root (KS-126) using a pentobarbital-induced sleep-acceleration test and polysomnographic recordings. Additionally, we investigated the molecular mechanism of KS-126 through patch-clamp electrophysiology. Our polysomnographic recordings revealed that KS-126 not only accelerated the onset of non-rapid eye movement sleep (NREMS) but also extends its duration. Considering the temporal dynamics of the sleep–wake stages, during the initial and subsequent periods KS-126 extended NREMS duration and decreased wakefulness, thereby enhancing sleep-promoting effects. Furthermore, the assessment of sleep quality via analysis of electroencephalogram power density indicated that KS-126 did not significantly alter sleep intensity. Finally, we found that KS-126 enhanced GABA<sub>A</sub> receptor-mediated synaptic responses in primary hippocampal neurons, leading to an increase in the percentage of the GABA current. This effect was not affected by the selective benzodiazepine receptor antagonist flumazenil, but was entirely inhibited by the GABA<sub>A</sub> receptor antagonist bicuculline. In conclusion, KS-126 extends the duration of NREMS without altering its intensity by prolonging GABAergic synaptic transmission, which modulates GABA<sub>A</sub> receptor function.
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