Emser, W and Bartylla, K. Improvement in Quality of Sleep: Effect of kava extract WS 1490 on the sleep patterns in healthy people Translation from TW Neurologie Psychiatrie. Vol. 5, Nov. 1991:663-642.[Ed. Note: Although this article was initially published in German in 1991. As a general rule, most articles summerized in HerbClipÖ are much more recent. However, because there is so much interest in kava and itsÆ potential to affect sleep patterns, HerbClipÖ decided to make this recent translation available despite itsÆ relatively small size and significance. ABC is grateful to Alden Botanica for supplying us with this translation for the benefit of the larger herbal community.]
This article examined the influence of kava extract WS 1490 (contained in Laitan, W. Schwabe; Karlsruhe, Germany) on the quality of sleep with healthy people. The standardized kava extract WS 1490 is derived from the rhizome (underground stem) of the kava plant (Piper methysticum) and contains 70 mg of kavalactones per 100 mg of extract. The effect of the kavalactones have been described by numerous authors in pharmacological and clinical studies as calming, muscle relaxing, anti-convulsive and anti-arrhythmic. Animal experiments by R. Kretzschmar and H.J. Teschendorf found that kavalactones increased sleep spindle density (sleep onset). In this article, this result was reproduced in healthy human subjects with kava extract WS 1490.
A total of 12 healthy subjects (3 women and 9 men), were split into two groups of 6 subjects per group with ages ranging from 20 to 31 years old. Most subjects did not have any objective sleep disturbances and no subject had alcohol or medication abuse, pain, or was suicidal. The primary objective of the study was the recording of the electroencephalograph (EEG) sleeping patterns of the subjects while undergoing treatments. Over a period of four days, the subjects in both groups were given a capsule three times a day in the following order:
Group A received a placebo on days 1, 3, and 4. On day 2, 50 mg. of kava extract WS 1490 was administered 3 times daily.
Group B received a placebo on days 1, 3, and 4. On day 2, 100 mg. of kava extract WS 1490 was administered 3 times daily.
The Medilog-Oxford Model 900, a long-time EEG system, was used over the testing period of 4 days and 4 nights to record four polygraphic EEG channels. Electromyograms (EMG) of the cervical and submental musculature and electrooculograms (EOG) were recorded. An independent person evaluated the EEGÆs. The enumeration of sleeping spindles in the sleep stage 2 (light sleep) was evaluated visually. The patients also filled out a questionnaire each day to subjectively record the quality of sleep and state of condition.
Effects of the Kava Extract While Sleeping
The following provides the details of the day the subjects were administered kava extract.
Sleep spindle densities for 11 of the 12 subjects increased around 20% in comparison with the densities recorded for placebo nights in both subject groups (see Figure 1 in the article for results).
The falling-asleep latency (time it takes to fall asleep), slow-wave-sleep latency (time it takes to move into deeper sleep stages) and REM latency (time it takes to move into the rapid eye movement sleep phase) were compared between groups (see Tables 1and Table 2 in the article). The lower dosage of kava extract, administered to group A, resulted in a decrease of falling-asleep latency in 5 of the 6 subjects and group B dosage resulted in a decrease in 4 of the 6 subjects, in comparison to the preceding placebo night. The slow-wave sleep latency did not change significantly for group A, but changed fairly significantly for group B, with the kava extract promoting a shorter slow-wave-sleep latency. The REM latency was decreased in only 2 subjects in group B, and was considered essentially unchanged in both groups.
The average percentages of the total sleep period were also assessed for the following EEG sleep stages: stage 1: falling-asleep, stage 2: light sleep, stage 3/4: deep sleep, REM stage: REM sleep (see Figure 2). The duration of the falling-asleep stage was decreased in 5 of 6 subjects in group B, in comparison with placebo. The smaller kava extract dose in group A had no influence on the falling-asleep stage. A minor decrease in light sleep occurred in both groups. Increases in the duration of deep sleep are seen for both groups where 11 of 12 subjects had increases, with more pronounced increase associated with group B subjects receiving the higher kava dose. REM sleep was decreased in only two subjects.
The average duration of the waking phase was also assessed (see Figure 3). The duration of the waking phase decreased in group B. Group A, receiving the smaller kava dose, showed virtually no change.
In contrast with the EEG results that displayed a decrease in falling-asleep latency, the falling-asleep latency increased according to subjective evaluation via the questionnaire. In agreement with the EEG results, the subjects cited an improvement in deep sleep, as well as an improvement in peace, calm and well-being in the morning after the kava extract night, which continued during the following 2 days in which a placebo was administered. The subjective responses by the subjects on the quality of sleep due to kava extract was very positive. No unwanted side-effects of the kava extract dosages were observed or felt by the subjects.
The authors summarize the following key points:
1.The increase in sleep spindle density in sleep EEG measurements is characteristic of conventional tranquilizers that is shared by the kava special extract WS 1490.
2.Sleep is favorably influenced through the use of kava special extract WS 1490. In particular, there is an increase of the duration of slow-wave sleep (deep sleep) and no change in the duration of REM sleep. The duration of sleep stage 1 (falling asleep stage), as well as the duration of the waking phase tend to decrease after higher kava extract dosages of 3 x 100 mg. The falling-asleep latency is reduced.
3.The kava extract studied here has no effect [on REM sleep]. No ôREM reboundö [excessive amounts of REM sleep] could be proven.
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