300–600 mg of extract, 30–60 min before bed.
Subjective improvement — inconsistent; depends on the extract
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Valerian is Valeriana officinalis, a perennial plant common in Europe and Asia whose dried root has documented medicinal use in European pharmacopeias since Greek and Roman antiquity as a mild sedative, anxiolytic, and sleep aid; it is one of the most studied medicinal plants for insomnia and mild anxiety, with modest but consistent clinical support that has led to its inclusion in official pharmacopeias as a herbal medicine with well-established use in Germany, the United Kingdom, and other European countries.
The active components identified are a complex mixture: valerenic acids and sesquiterpene derivatives (the compounds with the greatest documented pharmacological activity), valepotriates (with sedative activity but unstable in dry preparations), essential oil (with the characteristic unpleasant odor of the root), and other minor compounds; the proposed mechanism of action is multiple and includes modulation of the GABA-A receptor (mild potentiation of the effect of endogenous GABA, a mechanism analogous to that of benzodiazepines but significantly weaker), modulation of adenosine transport, and mild modulation of serotonergic receptors.
The indication with the most studied clinical support is mild to moderate functional insomnia: several randomized trials and meta-analyses have documented modest improvements in subjective sleep quality and reductions in sleep latency with doses of 300-900 milligrams of standardized dry extract taken 30-60 minutes before bedtime for weeks to months, with modest but clinically relevant effect sizes for mild insomnia and a tolerability profile significantly better than that of pharmacological hypnotics.
A meta-analysis published in the American Journal of Medicine in 2006 including 16 trials confirmed that valerian subjectively improves sleep quality, although objective polysomnographic effects are less consistent (small or non-significant improvements in objective parameters); clinical effects appear to accumulate with continued use over weeks, unlike pharmacological hypnotics, which have an acute effect from the first dose.
In mild anxiety, especially when associated with functional insomnia, several small studies have documented subjective improvements with supplementation at 600-900 mg/day for weeks; the effects are quantitatively smaller than those of benzodiazepines or specific SSRIs but may have a place as a first-line option in very mild presentations or as a complement to other interventions.
In climacteric symptoms, especially when they include sleep disturbances and anticipatory anxiety, valerian has shown significant improvements in some small studies, an indication consistent with its general effects and of reasonable integrative use.
The doses studied range from 300 to 900 milligrams of standardized dry extract for insomnia (typically 30-60 minutes before bedtime), or 300 mg two or three times a day for sustained anxiety; traditional preparations (root infusion, hydroalcoholic tincture) are gentle alternatives but have variable concentration and a characteristic unpleasant taste and smell that limit acceptability; dry extracts in capsules are the most practical form for sustained use; the effects on sleep and anxiety appear gradually and are optimal after 2-4 weeks of continued use.
Generally well tolerated at the doses studied; the most frequent adverse effects are residual daytime drowsiness (especially if taken too late or at high doses), occasional morning headache, vivid dreams, and occasionally, paradoxically, mild excitation (in a small proportion of people); people taking anxiolytics, sedatives, hypnotics, or antidepressants with a sedating profile may experience a mild potentiation of the effect and should use caution; those who drink alcohol may experience significant potentiation of the sedative effect and should avoid the combination; those taking drugs metabolized by cytochrome P450 may experience mild interactions; driving or operating dangerous machinery should be avoided during the hours after a dose if residual drowsiness is experienced; prolonged use (more than 4-6 continuous weeks) without breaks has been associated in some cases with withdrawal symptoms (rebound insomnia, transient anxiety) similar to those of benzodiazepines although significantly milder; in pregnancy and breastfeeding, data are limited and use is discouraged as a precaution; it is not recommended in children under 12 years; combinations with lemon balm, passionflower, hops, and other sedative herbs are common and may offer a synergistic profile with good tolerability; non-standardized products vary enormously in clinical efficacy, and it is advisable to choose products that declare their valerenic acid content.
Information, not medical advice. Scientific evidence reflects the quality of the studies.