Many addictions start as an attempt to escape from uncomfortable feelings such as low self esteem because we feel that we are not enough as we are. The yogic message is that you are complete as you are and so healing is a process of remembering who you really are. Much of this is initiated and maintained by what you stop doing (stopping drinking, smoking, drugs, eating unhealthy food, going to bed too late etc.) Here is a research paper on the positive outcomes for addicts using Kundalini yoga and meditation ; https://www.ncbi.nlm.nih.gov/pubmed/19842301
Yoga postures and deep breathing allow feelings to flow again. For those that are ready to rehabilitate (re-habit themselves) yoga and meditation is a very effective tool. Ironically there is often a lot of resistance to a regular yoga practice because as blocks are released so are the subconscious, irrational fears that put them there in the first place. Nevertheless once a daily practice is established Kundalini yoga remains the most effective technology for overcoming addictions.