Dr. Pannel also recommends valerian root for anxiety. "Research shows that when taken, it increases GABA or gamma aminobutyric acid, which is a known neurotransmitter that produces a calming effect," she explained. Dr. Pannel added that valerian root works best when it's taken for a few weeks and, at higher doses, it can also be used to treat insomnia. (Of course, you should always talk to your doctor if you're having trouble sleeping.)