Valerian is a supplement that has been used in Traditional Chinese Medicine for centuries to treat sleeplessness, anxiety, and stress. There is not much scientific research on valerian because it is not a mainstream medication, but there are some studies that have been conducted on valerian. Some of the studies have found that it can take up to 2 weeks for valerian to work. For most people, valerian does not appear to cause dependency. Nor does it cause withdrawal symptoms for most. But there are a few reports of withdrawal symptoms when valerian has been used over very long periods of time. If you want to stop taking valerian, lower your dose gradually rather than stopping all at once.