Some herbal supplements reduce anxiety without making you sleepy (such as L-theanine), while others are sedatives. Valerian (Valeriana officinalis) is squarely in the second category. It is a sleep aid, for insomnia. It contains sedative compounds; the German government has approved it as a treatment for sleep problems.
Valerian smells kind of nasty, so most people take it as a capsule or tincture, rather than a tea. If you want to try it, take it in the evening—not before you go to work! Valerian is often combined with other sedative herbs such as hops, chamomile, and lemon balm.