What is valerian?

Valerian (Valeriana officinalis), a member of the Valerianaceae family, is a perennial plant native to Europe and Asia and naturalized in North America. It has a distinctive odor that many find unpleasant. Other names include setwall (English), Valerianae radix (Latin), Baldrianwurzel (German), and phu (Greek). The genus Valerian includes over 250 species, but V. officinalis is the species most often used in the United States and Europe and is the only species discussed in this fact sheet.

Key points

This fact sheet provides an overview of the use of valerian for insomnia and other sleep disorders and contains the following key information:

• Valerian is an herb sold as a dietary supplement in the United States.
• Valerian is a common ingredient in products promoted as mild sedatives and sleep aids for nervous tension and insomnia.
• Evidence from clinical studies of the efficacy of valerian in treating sleep disorders such as insomnia is inconclusive.
• Constituents of valerian have been shown to have sedative effects in animals, but there is no scientific agreement on valerian's mechanisms of action.
• Although few adverse events have been reported, long-term safety data are not available.

What are common valerian preparations?

Preparations of valerian marketed as dietary supplements are made from its roots, rhizomes (underground stems), and stolons (horizontal stems). Dried roots are prepared as teas or tinctures, and dried plant materials and extracts are put into capsules or incorporated into tablets.

There is no scientific agreement as to the active constituents of valerian, and its activity may result from interactions among multiple constituents rather than any one compound or class of compounds. The content of volatile oils, including valerenic acids; the less volatile sesquiterpenes; or the valepotriates (esters of short-chain fatty acids) is sometimes used to standardize valerian extracts. As with most herbal preparations, many other compounds are also present.

Valerian is sometimes combined with other botanicals. Because this fact sheet focuses on valerian as a single ingredient, only clinical studies evaluating valerian as a single agent are included.

What are the historical uses of valerian?

Valerian has been used as a medicinal herb since at least the time of ancient Greece and Rome. Its therapeutic uses were described by Hippocrates, and in the 2nd century, Galen prescribed valerian for insomnia. In the 16th century, it was used to treat nervousness, trembling, headaches, and heart palpitations. In the mid-19th century, valerian was considered a stimulant that caused some of the same complaints it is thought to treat and was generally held in low esteem as a medicinal herb. During World War II, it was used in England to relieve the stress of air raids.

In addition to sleep disorders, valerian has been used for gastrointestinal spasms and distress, epileptic seizures, and attention deficit hyperactivity disorder. However, scientific evidence is not sufficient to support the use of valerian for these conditions.

What clinical studies have been done on valerian and sleep disorders?

In a systematic review of the scientific literature, nine randomized, placebo-controlled, double-blind clinical trials of valerian and sleep disorders were identified and evaluated for evidence of efficacy of valerian as a treatment for insomnia. Reviewers rated the studies with a standard scoring system to quantify the likelihood of bias inherent in the study design. Although all nine trials had flaws, three earned the highest rating (5 on a scale of 1 to 5) and are described below. Unlike the six lower-rated studies, these three studies described the randomization procedure and blinding method that were used and reported rates of participant withdrawal.

The first study used a repeated-measures design; 128 volunteers were given 400 mg of an aqueous extract of valerian, a commercial preparation containing 60 mg valerian and 30 mg hops, and a placebo. Participants took each one of the three preparations three times in random order on nine nonconsecutive nights and filled out a questionnaire the morning after each treatment. Compared with the placebo, the valerian extract resulted in a statistically significant subjective improvement in time required to fall asleep (more or less difficult than usual), sleep quality (better or worse than usual), and number of nighttime awakenings (more or less than usual).This result was more pronounced in a subgroup of 61 participants who identified themselves as poor sleepers on a questionnaire administered at the beginning of the study. The commercial preparation did not produce a statistically significant improvement in these three measures. The clinical significance of the use of valerian for insomnia cannot be determined from the results of this study because having insomnia was not a requirement for participation. In addition, the study had a participant withdrawal rate of 22.9%, which may have influenced the results.

In the second study, eight volunteers with mild insomnia (usually had problems falling asleep) were evaluated for the effect of valerian on sleep latency (defined as the first 5-minute period without movement). Results were based on nighttime motion measured by activity meters worn on the wrist and on responses to questionnaires about sleep quality, latency, depth, and morning sleepiness filled out the morning after each treatment. The test samples were 450 or 900 mg of an aqueous valerian extract and a placebo. Each volunteer was randomly assigned to receive one test sample each night, Monday through Thursday, for 3 weeks for a total of 12 nights of evaluation. The 450-mg test sample of valerian extract reduced average sleep latency from about 16 to 9 minutes, which is similar to the activity of prescription benzodiazepine medication (used as a sedative or tranquilizer). No statistically significant shortening of sleep latency was seen with the 900-mg test sample. Evaluation of the questionnaires showed a statistically significant improvement in subjectively measured sleep. On a 9-point scale, participants rated sleep latency as 4.3 after the 450-mg test sample and 4.9 after the placebo. The 900-mg test sample increased the sleep improvement but participants noted an increase in sleepiness the next morning. Although statistically significant, this 7-minute reduction in sleep latency and the improvement in subjective sleep rating are probably not clinically significant. The small sample size makes it difficult to generalize the results to a broader population.

The third study examined longer-term effects in 121 participants with documented nonorganic insomnia. Participants received either 600 mg of a standardized commercial preparation of dried valerian root (LI 156, Sedonium?*) or placebo for 28 days. Several assessment tools were used to evaluate the effectiveness and tolerance of the interventions, including questionnaires on therapeutic effect (given on days 14 and 28), change in sleep patterns (given on day 28), and changes in sleep quality and well-being (given on days 0, 14, and 28). After 28 days, the group receiving the valerian extract showed a decrease in insomnia symptoms on all the assessment tools compared with the placebo group. The differences in improvement between valerian and placebo increased between the assessments done on days 14 and 28.

The reviewers concluded that these nine studies are not sufficient for determining the effectiveness of valerian to treat sleep disorders. For example, none of the studies checked the success of the blinding, none calculated the sample size necessary for seeing a statistical effect, only one partially controlled prebedtime variables, and only one validated outcome measures.

Two other randomized, controlled trials published after the systematic review described above are presented below.

In a randomized, double-blind study, 75 participants with documented nonorganic insomnia were randomly assigned to receive 600 mg of a standardized commercial valerian extract (LI 156) or 10 mg oxazepam (a benzodiazepine medication) for 28 days. Assessment tools used to evaluate the effectiveness and tolerance of the interventions included validated sleep, mood scale, and anxiety questionnaires as well as sleep rating by a physician (on days 0, 14, and 28). Treatment result was determined via a 4-step rating scale at the end of the study (day 28). Both groups had the same improvement in sleep quality but the valerian group reported fewer side effects than did the oxazepam group. However, this study was designed to show superiority, if any, of valerian over oxazepam and its results cannot be used to show equivalence.

In a randomized, double-blind, placebo-controlled crossover study, researchers evaluated sleep parameters with polysomnographic techniques that monitored sleep stages, sleep latency, and total sleep time to objectively measure sleep quality and stages. Questionnaires were used for subjective measurement of sleep parameters. Sixteen participants with medically documented nonorganic insomnia were randomly assigned to receive either a single dose and a 14-day administration of 600 mg of a standardized commercial preparation of valerian (LI 156) or placebo. Valerian had no effect on any of the 15 objective or subjective measurements except for a decrease in slow-wave sleep onset (13.5 minutes) compared with placebo (21.3 minutes). During slow-wave sleep, arousability, skeletal muscle tone, heart rate, blood pressure, and respiratory frequency decreased. Increased time spent in slow-wave sleep may decrease insomnia symptoms. However, because all but 1 of the 15 endpoints showed no difference between placebo and valerian, the possibility that the single endpoint showing a difference was the result of chance must be considered. The valerian group reported fewer adverse events than did the placebo group.

Although the results of some studies suggest that valerian may be useful for insomnia and other sleep disorders, results of other studies do not. Interpretation of these studies is complicated by the fact the studies had small sample sizes, used different amounts and sources of valerian, measured different outcomes, or did not consider potential bias resulting from high participant withdrawal rates. Overall, the evidence from these trials for the sleep-promoting effects of valerian is inconclusive.