Adults may take valerian one to two hours before sleep. It can be taken up to three times a day, with the final dose soon before bedtime, according to the University of Maryland Medical Center.
Valerian may need to be taken for 2 to 6 weeks until sleep improves, and its full effects may not be felt for a few weeks. Other sedating herbs such as hops and lemon balm are often combined with valerian to treat insomnia. Consult a physician before giving valerian to a child. The normal dose of valerian for insomnia is 300 to 900 milligrams in tablet form, as stated by the American Cancer Society. For stress and anxiety, the recommended dose is 50 to 100 milligrams taken two to three times a day. In some cases as much as 200 to 400 milligrams is recommended.