The plant’s dried root contains valepotriates, which may have calming effects.
People take valerian mostly as a sedative and sleep aid, especially in parts of Europe. In two relatively well-designed studies, valerian improved sleep quality and shortened the time needed to fall asleep.
Some people take valerian for headaches, depression, irregular heartbeat, and trembling. It is usually used for short periods of time (4 to 6 weeks). There is not enough scientific evidence to determine whether valerian is effective for these conditions.
Headaches, excitability, uneasiness, and heart disturbances have been reported. People who are driving or doing other activities requiring alertness should not take it. Other side effects include upset stomach, dizziness, and tiredness.
Valerian may prolong the effect of other sedatives (such as barbiturates) when it is taken with them.
Valerian is not recommended for women who are pregnant or breastfeeding.