valerian root does several beneficial things, all seemingly without side effects. IT does help you go to sleep, but it also encourages dopamine production during sleep, so you sleep more effectively. Increased dopamine production during sleep encourages better serotonin production during the
day. This is an effective theraputic way to relieve and prevent anxiety, as opposed to drugs.
In addition it is an 'anti-spasmodic' muscle relaxer meaning that it prevents muscles from knotting up or cramping. With long term therapy it can also permanently lower bloodpressure. It's been studied extensively in the UK , and if I understand correctly has been proven to be quite safe.
I take one capsule before bed. The only side effect I have noticed is that sometimes I can remember my dreams quite vividly. I do take an extra one during the day if I'm really stressed, but usually I don't need one. Do not take two and try to drive!
I found a good book called 'Healing Anxiety With Herbs' that gave good information.