Valeriana officinalis has been a medicinal herb since at least the first century AD, when Dioscorides described its use for sleep and nervous conditions in his foundational herbal text. In medieval Europe it was used as a tranquilizer and anticonvulsant. During World War II it was used by civilians in England to manage anxiety from air raids. Today it sits in the top tier of herbal supplement sales globally — and the scientific evidence supporting its traditional uses has grown substantially.
The Active Compounds
Valerian root's pharmacology is complex and involves multiple compound classes working through complementary pathways. The major players are valerenic acid and its derivatives, isovaleric acid, and a variety of iridoids (valepotriates) and flavonoids.
Valerenic Acid and GABA
Valerenic acid has been shown to act as a positive allosteric modulator of GABA-A receptors — the same mechanism as benzodiazepines and alcohol, but with key differences. Valerenic acid's modulation is subunit-selective (affecting beta2 and beta3 subunits) in a way that produces sedation without the cognitive impairment, respiratory depression risk, or dependence liability of pharmaceutical GABA-A modulators. This subunit selectivity is believed to be why valerian produces fewer side effects than benzodiazepines despite a mechanistic overlap.
Valerenic acid also inhibits the enzyme responsible for GABA degradation (GABA transaminase), effectively increasing GABA availability in the synaptic cleft. This dual action — potentiating GABA receptors while increasing GABA levels — is a more powerful mechanism than either effect alone.
Adenosine Receptor Activity
Valerian extracts have also been shown to inhibit adenosine uptake, increasing extracellular adenosine levels. Adenosine accumulates in the brain during waking hours and is a primary driver of sleep pressure (the build-up of the need to sleep). Caffeine's alerting effect works by blocking adenosine receptors; valerian's opposing effect by increasing adenosine signaling is mechanistically sound.
Clinical Evidence
Sleep Onset and Quality
A 2006 meta-analysis in the American Journal of Medicine reviewed 16 randomized controlled trials of valerian for sleep quality. The majority of studies reported improvement in sleep quality without side effects, with the most consistent finding being improved sleep onset latency (time to fall asleep). Effect sizes were modest in individual trials but consistent across studies.
A 2011 Cochrane-level systematic review evaluated valerian in 18 randomized trials and found 'suggestive evidence that valerian may improve sleep quality without producing side effects.' The reviewers noted that heterogeneity in preparations and doses complicated meta-analysis — a common challenge in botanical research.
Anxiety
A 2002 study in Phytomedicine found that a valerian-hops combination significantly reduced state anxiety compared to placebo in a stressful situation. A 2014 study in Psychopharmacology found valerian extract to produce significant anxiolytic effects in healthy volunteers in a validated anxiety provocation paradigm.
Menopause and Menopausal Sleep
Multiple trials have found valerian to improve sleep quality in menopausal and postmenopausal women specifically — a population where sleep disruption is disproportionately prevalent and where pharmaceutical sleep aids carry particular risks. A 2011 RCT in Menopause found valerian significantly improved sleep quality scores and reduced sleep disruption in this population.
I'm a sleep medicine physician and I recommend valerian regularly for patients who want a non-pharmaceutical option. The mechanistic data is solid and the side effect profile over 30+ years of widespread use is very clean. It doesn't work for everyone — nothing does — but it's a legitimate first-line option for mild to moderate sleep difficulty. — Sleep medicine physician, Boston
Formulation: The Valerian-Hops Combination
Valerian is frequently combined with hops (Humulus lupulus) in sleep formulations — a pairing supported by traditional use and clinical research suggesting additive or synergistic effects. Hops contain 2-methyl-3-buten-2-ol, a compound that potentiates GABA-A receptors through mechanisms complementary to valerenic acid. The combination consistently outperforms either component alone in clinical comparisons.