Valerian (Valeriana officinalis) has a long history of traditional use for alleviating stress, anxiety, and sleep disturbances. Scientifically, valerian is best known for its sedative and anxiolytic (anxiety-reducing) effects, which are thought to be mediated through modulation of gamma-aminobutyric acid (GABA) neurotransmission in the brain. Several small randomized controlled trials and systematic reviews have examined valerian's impact on stress and related symptoms. Some studies suggest mild reductions in subjective stress and anxiety, but methodological limitations—such as small sample sizes, variability in valerian preparations, and inconsistent outcome measures—make the overall evidence modest at best.

The 2020 Cochrane review on valerian for anxiety disorders concluded that there is insufficient evidence to determine its efficacy for anxiety, which is closely related to stress. For general stress support, the European Medicines Agency recognizes valerian as a traditional herbal remedy for mild nervous tension, acknowledging widespread traditional use but limited high-quality scientific validation. Adverse effects are generally mild and infrequent.

In summary, while valerian is traditionally used for stress and there is some scientific evidence suggesting a mild benefit, the quality and quantity of clinical research do not robustly support its use for stress reduction. The evidence rating is therefore 2 out of 5, indicating weak scientific support.