Valerian is a herb extracted from the root of—you guessed it—the valerian plant, which grows across Europe, Asia, and North America. The perennial is quick to grow and easy to maintain, making it a popular garden option around the world. Its roots have been harnessed for their medicinal qualities for centuries, and today you can find them in powder, liquid, and capsule form. Dried valerian root can also be steeped as an herbal tea.
Valerian has long been used as a mild sedative, but research into its efficacy as a sleep aid has brought up some mixed results. One 1996 study on 121 patients found that dried valerian root could decrease insomnia symptoms when taken at bedtime for 28 days, compared to a placebo. However, during a more recent trial on 16 women with insomnia, valerian did not appear to improve sleep after two weeks.
After reviewing the pool of existing research, the NIH declared that there is not enough evidence to determine the effectiveness of valerian to treat sleep disorders. The studies that have been conducted on it so far vary widely in their methods of data collection, and some combine valerian with other calming plants like hops, making it difficult to say whether the ingredient works or doesn’t work on its own. Since valerian is a natural plant compound, its potency will also vary depending on how and where it was harvested, the NIH says, and some people might glean more benefits from taking it in certain forms over others.
Potential side effects of taking valerian root include nausea and abdominal cramps.