Valerian is TOXIC in high doses!!
Parts used: roots
The active ingredient is water soluble, so it can be used as a tea.
Valerian has a tranquilizing effect and is good for nervous tension, headaches, and insomnia (that, I think I can attest to--add a glass of red wine to a valerian tincture...Zzzzzzz).
It has a sedative effect on the Central Nervous System, strengthens the heart (especially good for heart palpatations), lowers high blood pressure, and relieves menstrual cramps.
I made a tincture of valerian and am dropping 10 drops (and up to a teaspoon) in a cup of chamomile tea for cramps. It seems to have helped (or maybe it was all those weird Ayurvedic herbs). I am going to make sure I always have a valerian tincture around for headaches, pain, and cramps! I can sleep the pain away...
(Sorry Mark, I'm not sure this is the herb you meant either!)