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Passionflower

In spite of the name, this herb won't help you in love. It's a sedative; the German government has approved it for nervous restlessness. Some studies find that it can reduce symptoms of anxiety as effectively as prescription drugs. It's often used for insomnia.

Like other sedatives, it can cause sleepiness and drowsiness, so don't take it—or valerian, hops, kava, lemon balm, or other sedative herbs—when you are also taking a prescription sedative.