Valerian root shows up in more sleep supplements than almost any other botanical, usually with a vague "traditional use for centuries" line and not much else. That's a shame, because valerian is one of the few sleep herbs with a real, if messy, body of clinical trial data behind it. Here's what the research actually says about how it works, how well it works, what dose it takes to get there, and where it fits next to something like a purpose-built Sleep Formula.
What valerian root is
Valerian (Valeriana officinalis) is a flowering plant whose root has been used as a folk sedative since at least ancient Greece. Modern supplements use dried root, root extracts, or tinctures, standardized (when they're standardized at all) to valerenic acid content — one of the compounds thought to be behind its effects. It's sold on its own as capsules or tea, and it's a common component in multi-ingredient sleep blends. When it appears inside a blend without an individual amount on the panel, the label arithmetic in our proprietary-blend guide is the only way to judge whether it could plausibly be at a studied dose.
The proposed mechanism: GABA, not brute-force sedation
Valerian's leading mechanistic hypothesis centers on GABA — gamma-aminobutyric acid, the brain's main inhibitory neurotransmitter, the same system benzodiazepines and z-drugs act on. Valerenic acid appears to act as a positive modulator at GABA-A receptors, similar in direction (though far weaker) to how benzodiazepines work.1 Separately, valerian may inhibit the enzyme that breaks GABA down, potentially raising GABA levels in the synapse rather than just amplifying its receptor effect.2 The exact active constituent responsible for sleep effects in humans still isn't settled — valerian is a mixture of dozens of compounds, and which ones matter most in vivo is genuinely unresolved. It's worth noting that acting on the GABA system from the outside is a different proposition from swallowing GABA itself, which runs into the blood-brain barrier.
What the trials actually show
The honest answer is: mixed, with a subjective positive signal that mostly disappears when you look at objective measurements. Individual trials are all over the map — some show valerian beating placebo on sleep latency and quality, others show no difference at all. That inconsistency comes from real methodological noise: different extracts, different doses, different durations, and outcomes measured largely by self-report rather than polysomnography.
The 2023 meta-analysis by Zhang and colleagues, pooling 21 RCTs in 1,433 participants, is the most useful single summary, and it splits cleanly along the subjective/objective line:4
- Subjective — positive. PSQI score improved with a small-to-moderate effect (SMD −1.21; 95% CI −1.92 to −0.51); self-reported sleep quality improved (RR 1.37; 95% CI 1.13 to 1.68); self-reported sleep duration improved (RR 1.27; 95% CI 1.02 to 1.57).
- Objective — almost entirely null. The one significant polysomnographic finding was the length of NREM stage 3 sleep (SMD 0.89; 95% CI 0.35 to 1.43). Other objective parameters showed no statistically significant improvement. Heterogeneity across trials came from preparation, outcomes, follow-up duration and populations.
An earlier meta-analysis of 18 placebo-controlled trials is even more sobering once you read past the headline. It ran three separate analyses, and two of them found nothing: the mean difference in sleep latency between valerian and placebo was 0.70 minutes (95% CI −3.44 to 4.83) — a confidence interval straddling zero — and the standardised mean difference in sleep quality measured on visual analogue scales was −0.02 (95% CI −0.35 to 0.31), also null.5 Only the dichotomous, yes/no outcome — did the participant report their sleep quality improved — was significant, at a relative risk of 1.37 (95% CI 1.05 to 1.78). The authors' own conclusion is worth quoting: valerian "would be effective for a subjective improvement of insomnia, although its effectiveness has not been demonstrated with quantitative or objective measurements," and they recommend "future investigations oriented toward improving insomnia with other more promising treatments." An earlier version of this article summarised that as a "statistically significant but modest effect," which was too generous by half.
Put those two meta-analyses side by side and a consistent picture emerges: people report sleeping better on valerian; instruments largely don't detect it. That is not proof it does nothing — subjective sleep quality is what people actually care about, and it's a legitimate outcome — but it is a long way from what the marketing implies. For a treatment where both subjective and objective measures move, CBT-I is the comparison.
People report sleeping better on valerian. Sleep-lab instruments mostly don't detect it. Both of those are findings, and only one of them makes it into marketing copy.
Dose: what's actually been studied
Trials have used a wide range of preparations and doses. The NIH Office of Dietary Supplements describes studies using 400mg of aqueous extract, 450–900mg of aqueous valerian extract, and 600mg of a standardized commercial preparation (LI 156) taken over 28 days, along with combination products.7 Very little of the literature tests doses below 300mg on their own. A randomized, double-blind crossover trial in 39 hemodialysis patients found valerian taken an hour before sleep for a month produced significantly greater reductions in Pittsburgh Sleep Quality Index, depression and state anxiety scores than placebo — a useful example of the subjective signal, in a specific clinical population.3
| Source | Valerian dose used |
|---|---|
| Typical published RCTs | 300–900 mg extract, once daily |
| NIH Office of Dietary Supplements examples | 400 mg and 450–900 mg aqueous extract; 600 mg standardized (LI 156) over 28 days |
| Proco Sleep Formula | 150 mg, as one of seven disclosed actives |
That 150mg puts Sleep Formula's valerian content below the range used in the trials showing a benefit. We're not going to pretend otherwise. In Sleep Formula, valerian is one of seven disclosed ingredients — alongside chamomile 100mg, GABA 100mg, L-tryptophan 100mg, lemon balm 100mg, passion flower 100mg and melatonin 2mg — and the dose reflects a stacking approach, not a claim that 150mg alone replicates the effect sizes from higher-dose single-ingredient trials. If you want valerian specifically at the doses most studies have tested, a standalone valerian product at 300mg or more is the more direct way to test it for yourself. Inside Sleep Formula goes through every amount, and the non-melatonin sleep aids with the best support puts valerian in context against the alternatives.
Side effects and who should be cautious
Valerian is generally well tolerated in trials. Per the NIH Office of Dietary Supplements, "headaches, dizziness, pruritus, and gastrointestinal disturbances are the most common effects reported in clinical trials but similar effects were also reported for the placebo."7 On the next-day grogginess people ask about: one study reported an increase in sleepiness the morning after 900mg of valerian was taken — so the "hangover" concern is not imaginary, and it appears at the higher end of the dose range.7
The more important caution is additive sedation. NIH flags potential interactions with benzodiazepines (alprazolam, diazepam, lorazepam, triazolam) and with barbiturates or other CNS depressants such as phenobarbital, morphine and propofol.7 Alcohol belongs in the same conversation — see our guide to Proco supplements and alcohol. On stopping: the evidence is a single case report of cardiac complications and delirium associated with valerian root withdrawal, with no systematic data on discontinuation.7 One case report is not a pattern, but tapering rather than stopping abruptly is the more cautious approach after a long nightly stretch.
Bottom line
Valerian root isn't a myth and it isn't a miracle. At the level of individual trials the evidence is genuinely mixed; pooled, it points to a modest benefit for subjective sleep quality and very little on objective measures. That's enough to justify including it in a formula and nowhere near enough to justify overselling it. If you're looking at a product with valerian in it, check the dose against what's actually been studied, watch for it stacked with other sedating compounds or alcohol, and treat "some people report sleeping better" as the accurate claim rather than "cures insomnia."
This article is for informational purposes only and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease. Speak with a healthcare provider before starting any new supplement, especially if you take medication or have an existing health condition.
References
- Benke D, et al. "GABA A receptors as in vivo substrate for the anxiolytic action of valerenic acid, a major constituent of valerian root extracts." Neuropharmacology, 2009. pubmed.ncbi.nlm.nih.gov/18602406
- Ortiz JG, et al. "Effects of Valeriana officinalis extracts on [3H]flunitrazepam binding, synaptosomal [3H]GABA uptake, and hippocampal [3H]GABA release." Neurochemical Research. Discussed in National Center for Complementary and Integrative Health (NCCIH), "Valerian." nccih.nih.gov/health/valerian
- Tammadon MR, Nobahar M, Hydarinia-Naieni Z, Ebrahimian A, Ghorbani R, Vafaei AA. "The Effects of Valerian on Sleep Quality, Depression, and State Anxiety in Hemodialysis Patients: A Randomized, Double-blind, Crossover Clinical Trial." Oman Medical Journal, 2021. pmc.ncbi.nlm.nih.gov/articles/PMC8077445
- Zhang Y, Lu M, Lv Y, Hu X, Yao J, Wu S, Lian C, Yang Y, Xu H. "Valerian for Insomnia on Subjective and Objective Sleep Parameters: a Meta-analysis of Randomized Controlled Trials." Current Sleep Medicine Reports, 2023. link.springer.com/article/10.1007/s40675-023-00259-4
- Fernández-San-Martín MI, Masa-Font R, Palacios-Soler L, Sancho-Gómez P, Calbó-Caldentey C, Flores-Mateo G. "Effectiveness of Valerian on insomnia: a meta-analysis of randomized placebo-controlled trials." Sleep Medicine, 2010;11(6):505-511. pubmed.ncbi.nlm.nih.gov/20347389
- National Center for Complementary and Integrative Health (NCCIH). "Valerian: Usefulness and Safety." nccih.nih.gov/health/valerian
- National Institutes of Health, Office of Dietary Supplements. "Valerian — Health Professional Fact Sheet." ods.od.nih.gov/factsheets/Valerian-HealthProfessional
Related reading: Inside Sleep Formula: what's in it and why · Chamomile for sleep and anxiety: what the research shows
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