More than 200 plant species belong to the genus Valeriana,but the one most commonly used as an herb is Valeriana officinalis.The root is used for medicinal purposes.
Galen recommended valerian for insomnia in the second century AD. From the sixteenth century onward, this herb became popular as a sedative in Europe (and later, the United States). Scientific studies on valerian in humans began in the 1970s, leading to its approval as a sleep aid by Germany's Commission E in 1985. However, the scientific evidence showing that valerian really works remains incomplete.
As with most herbs, we are not exactly sure which ingredients in valerian are most important. ^ Early research focused on a group of chemicals known as valepotriates, but they are no longer considered candidates. A constituent called valerenic acid has also undergone study, but its role is far from clear. Another substance in valerian, called linarin, has also attracted research interest. ^ Our understanding of how valerian might function remains similarly incomplete. Several studies suggest that valerian affects GABA, a naturally occurring amino acid that appears to be related to the experience of anxiety. ^ ^ ^ Conventional tranquilizers in the Valium family are known to bind to GABA receptors in the brain, and valerian may work similarly. However, there are some significant flaws in these hypotheses, and the reality is that we don't really know how valerian works (or if, indeed, it really does). ^
For insomnia, the standard adult dosage of valerian is 2 g to 3 g of dried herb, 270 mg to 450 mg of an aqueous valerian extract, or 600 mg of an ethanol extract, taken 30 to 60 minutes before bedtime. ^ The same amount, or a reduced dose, can be taken twice daily for anxiety.
Because of valerian's unpleasant odor, European manufacturers have created odorless valerian products. However, these are not yet widely available in the United States.
Valerian is not recommended for children under 3 years old. ^
What Is the Scientific Evidence for Valerian?
Overall, the evidence supporting valerian as a sleep aid remains substantially incomplete and self-contradictory. ^ A systematic review published in 2007 concluded that valerian is probably not effective for treating insomnia. ^ However, there have been some positive results, both with valerian alone and valerian combined with other herbs.
The best positive study of valerian for insomnia followed 121 people for 28 days. ^ In this double-blind, placebo-controlled trial, half of the participants took 600 mg of an alcohol-based valerian extract 1 hour before bedtime, while the other half took placebo. Valerian didn't work right away. For the first couple of weeks, valerian and placebo were running neck and neck. However, by day 28, valerian pulled far ahead. Effectiveness was rated as good or very good by participant evaluation in 66% of the valerian group and in 61% by doctor evaluation, whereas in the placebo group, only 29% were so rated by participants and doctors.
Although positive, these results are a bit confusing. In another large study, valerian was immediatelymore effective than placebo, which is more in keeping with how the herb is typically used. This trial followed 128 subjects who had no sleeping problems. ^ On nine nonconsecutive nights, each participant took one of three treatments: valerian, a combination of valerian and the herb hops , or placebo. The results showed that on the nights they took valerian alone, participants fell asleep faster than when they were taking placebo, or the combination. In contradiction to this, other studies have failed to find any immediate mental depressant effects with valerian; most substances that rapidly induce sleep also sedate the mind. ^ Furthermore, the more recent and best designed studies have generally failed to find valerian more helpful at all. ^ One of these was a 4-week study in which 135 people were given valerian and 135 given placebo. ^ Another was a two-week study of 405 people which found “modest benefits at most[italics added.]” ^ A 6-week, double-blind study of 202 people with insomnia compared valerian extract (600 mg at bedtime) with the standard drug oxazepam (10 mg at bedtime) and found equal efficacy. ^ Equivalent benefits were also seen in similar study of 75 people. ^ However, the absence of a placebo group in these two studies decreases the reliability of the results.
A study of 184 people tested a standardized combination of valerian and hops, with mixed results. ^ Researchers tested quite a few aspects of sleep (such as time to fall asleep, length of sleep, number of awakenings) and found evidence of benefit in only a few. This use of “multiple outcome measures” makes the results somewhat unreliable.
A much smaller study also found evidence that a combination of hops and valerian extract is more effective as a sleep aid than placebo; the results of this trial also hint that hops plus valerian is more effective than valerian alone, but this possible finding did not reach statistical significance. ^ A double-blind comparative study that enrolled 46 patients compared the effects of the standard drug bromazepam to a mixture of valerian and hops with either treatment taken one-half hour before bed. ^ The results suggest that the two treatments were equally effective. One study found that this valerian-hops combination can antagonize the arousal produced by caffeine. ^ A combination of valerian and lemon balm has also been tried for insomnia. A rather poorly designed 30-day, double-blind, placebo-controlled study of 98 individuals without insomnia found marginal evidence that a valerian-lemon balm combination improved sleep quality as compared to placebo. ^ However, a double-blind crossover study of 20 people with insomnia compared the benefits of the sleeping drug Halcion (0.125 mg) against placebo and a combination of valerian and lemon balm, and failed to find the herb effective. ^ The drug, however, did prove effective.
Valerian has shown some promise for helping people sleep better after discontinuing conventional sleeping pills in the benzodiazepine family. ^
In a double-blind, placebo-controlled study, 36 people with generalized anxiety disorder were given either valerian extract, Valium, or placebo for a period of 4 weeks. ^ The study failed to find statistically significant differences between the groups, presumably due to its small size.
Valerian has also been tested for possible benefits during stressful circumstances. Two preliminary double-blind studies found weak evidence that valerian may produce calming effects in induced stressful situations. ^ Another study evaluated the effects of a combination containing valerian and lemon balm taken in various doses. ^ Some benefits were seen with doses of 600 mg or 1200 mg three times daily, but the highest dose (1,800 mg 3x daily) actually appeared to increaseanxiety symptoms during a stressful situation. Furthermore, people taking the herbal treatment at any dose showed slightly decreased cognitive function as compared to those given placebo.