Although we usually hear about rehab facilities when it involves a celebrity struggling with some form of addiction - the reality is, places like the Betty Ford Clinic are there to help everyday people deal with addiction issues. But how does rehab work? And how does someone become addicted to a substance? To find out, Rod spoke with Professor Keith Humphreys, a professor of Psychiatry at Stanford university who has served as a drug policy advisor in both the Bush and Obama White houses.