If you do a quick search about the valerian root, you’ll find plenty of places selling it, but a strange lack of information about its actual effects. Dig deeper and you’ll discover that valerian root is a special kind of homeopathic medicine - unlike many other herbs and home medications, the root has actually shown promising results in scientific studies.
The root’s euphoric effect on cats is also well-known and easily proven. Just give your cat a bit of the root, and if he’s susceptible to its effects, he’ll go wild biting it, rubbing his face in it, drooling, and generally acting kitten-like. There is no solid scientific answer behind why it works, but that’s also true for catnip!