Valerian is a perennial flowering plant native to Europe and Asia. In the summer when the mature plant may have a height of 1.5 metres, it bears sweetly scented pink or white flowers that attract many fly species, especially hoverflies of the genus Eristalis. It is consumed as food by the larvae of some Lepidoptera species, including the grey pug.

A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but the majority of them affect the neurotransmitter gamma-aminobutyric acid (GABA). In spite of the fact that each sedative acts in its own way, most produce relaxing effects by increasing GABA activity.