Cannabidiol (CBD) is a cannabinoid found in Cannabis. It is a major constituent of the plant, representing up to 40% in its extracts.
CBD alone is NOT INTOXICATING but displayed sedative effects in animal tests. Some research, however, indicates that CBD can increase alertness. It may decrease the rate of THC clearance from the body, perhaps by interfering with the metabolism of THC in the liver.
Medically, it has been shown to relieve convulsion, inflammation, anxiety, and nausea, and to inhibit cancer cell growth. Recent studies have shown cannabidiol to be as effective as atypical antipsychotics in treating schizophrenia.
***In November 2007 it was reported that CBD reduces growth of aggressive human breast cancer cells in vitro and reduces their invasiveness. It thus represents the first non-toxic exogenous agent that can lead to down-regulation of tumor aggressiveness. It is also a neuroprotective antioxidant.***
A 2008 study published in the British Journal of Psychiatry showed significant differences in Oxford-Liverpool Inventory of Feelings and Experiences scores between three groups: The first consisted of non-cannabis users, the second of users who tested positive for Δ9-THC only, and the third consisted of users who tested positive for both Δ9-THC and CBD. The Δ9-THC only subset scored significantly higher for unusual experiences, while users of both Δ9-THC and CBD had much lower introvertive anhedonia scores . 
With benefits like this.... they really should.....