Since the discovery of photic driving by Adrian and Matthews in 1934, much has been discovered about the benefits of brainwave entrainment (BWE) or audio-visual entrainment (AVE) as it is commonly known today. AVE affects cerebral blood flow, neurotransmitters, dissociative states and brainwave activity. Research on the effectiveness of AVE in promoting relaxation, cognition and hypnotic induction, treating ADD, PMS, SAD, PTSD, migraine headache, chronic pain, anxiety, depression and hypertension is now available. This research will be reviewed in detail, including the most recent studies. The physiological and/or psychological aspects of the treatment will be explained.