Here are a couple of links that you may find helpful.
I generally take nothing but herbal supplements. You always have to be careful because there are definately things you should not mixed. Valerian root should not be mixed with anti depressants and others benzos (refer to emedtv.com-great place for all info) I do primarily natural medicine and many conventional health care providers are in the dark regarding these supplements. The website about is great but you can always google a supplement and find many great websites. Though many people are not so evolved regarding alternative health care there are many of us who have done it for years and strongly believe in it. I would suggest to find a reputable source (such as a natural doctor) for any supplements to gaurantee product reliability. Good luck.