Effects of red ginseng extract on sleep architecture and electroencephalogram power spectra in rats

Sleep-Aids Derived from Natural Products

Although drugs such as barbiturates and benzodiazepines are often used for the treatment of insomnia, they are associated with various side effects such as habituations, tolerance and addiction. Alternatively, natural products with minimal unwanted effects have been preferred for the treatment of acute and/or mild insomnia, with additional benefits of overall health-promotion. Basic and clinical researches on the mechanisms of action of natural products have been carried out so far in insomnia treatments. Recent studies have been focusing on diverse chemical components available in natural products, with an interest of developing drugs that can improve sleep duration and quality. In the last 15 years, our co-workers have been actively looking for candidate substances from natural products that can relieve insomnia. This review is, therefore, intended to bring pharmacological data regarding to the effects of natural products on sleep duration and quality, mainly through the activation of GABA_A receptors. It is imperative that phytochemicals will provide useful information during electroencephalography (EEG) analysis and serve as an alternative medications for insomnia patients who are reluctant to use conventional drugs.

Effects of red ginseng extract on sleeping behaviors in human volunteers

ETHNOPHARMACOLOGICAL RELEVENCE

The ginseng root has been traditionally used as a sedative in oriental countries. However, the condition "ginseng abuse syndrome" (GAS), defined as hypertension, nervousness, sleeplessness, skin eruption, and morning diarrhea, was coined as a result of a study of people who had been using a variety of ginseng preparations. However, we reported that administration of RGE increased rapid eye movement (REM) and non rapid eye movement (NREM) sleep via GABAergic systems in animals. Therefore, this study was performed to investigate how red ginseng extract (RGE) affects sleeping behaviors in human volunteers.

MATERIALS AND METHODS

RGE (1500 mg) was orally administered to young male healthy volunteers (from 15 to 37 years old ages, n=15) three times a day for 7 days. Overnight polysomnographic (PSG) studies were performed two times, 1 day before and 7 days after RGE administration. We investigated differences in sleep architecture parameters such as total sleep time (TST), sleep efficacy (SE: total sleep time/time in bed), proportion of each sleep stage, and wakefulness after sleep onset (WASO) between baseline PSG and PSG after RGE administration.

RESULTS

Total wake time (TWT) was significantly reduced (P<0.05) and SE was increased (P<0.05), although slow wave sleep stage 1 (N1) was reduced (P<0.01) and non-rapid eye movement (REM) sleep was increased (P<0.03) after administration.

CONCLUSION

From these results, it is presumed that RGE intake would improve the quality of sleep, thus having beneficial effects on sleep disturbed subjects.

Hypnotic effects and binding studies for GABA(A) and 5-HT(2C) receptors of traditional medicinal plants used in Asia for insomnia

AIM OF THE STUDY

Many medicinal plants have been used for treatment of insomnia in Asia. However, scientific evidence and precise mechanism for their sedative-hypnotic activity have not been fully investigated. Thus, we investigated the binding activity of the oriental plant extracts (mainly from Korea and Japan) to the well-known molecular targets for sleep regulation, GABA(A) and 5-HT(2C) receptors. Following the binding assay, sedative-hypnotic effects of the extracts with high affinity were examined in an animal model of sleep.

MATERIALS AND METHODS

Aqueous and ethanol extracts of 15 medicinal plants were tested for binding at the benzodiazepine site of GABA(A) receptor and 5-HT site of 5-HT(2C) receptor. The sedative-hypnotic effects of selected extracts were evaluated by measuring the sleep latency and sleep duration during pentobarbital-induced sleep in mice after oral administration of extracts.

RESULTS

In the GABA(A) assay, the ethanol extracts of licorice and danshen displayed concentration-dependent, high affinity binding, whereas in the 5-HT(2C) assay, the ethanol extracts of ginseng and silk tree showed high affinity. Among these extracts we tested previously uncharacterized licorice and silk tree for hypnotic effects. We found the ethanol extracts of licorice and silk tree significantly decreased sleep latency and increased sleep duration in pentobarbital-induced sleep.

CONCLUSIONS

We demonstrate for the first time that licorice and silk tree have the sedative-hypnotic activity possibly by modulating GABA(A) and 5-HT(2C) receptors. We propose that licorice and silk tree might be effective candidates for treatment of insomnia.