I have been a Reiki teacher/practitioner for the past 11 years. I have seen people come out of comas (in IC units in hospitals), I've seen healings of bone fractures sped up by e weeks-through a body cast, I've seen cancer go into remission, Reiki is great for the healing of emotions and hurtful memories especially with people who have experienced physical or sexual abuse, and I could go on. Reiki is energy healing and spiritual development of one's personal gifts. It works because the energy of the divine is in union with a person's personal energy to affect healing and development.
Fortunately there are clinical studies occurring all over the world in hospitals and health centers with Reiki in different areas of health care - do a google search of Reiki and clinical studies and you will be amazed at what comes up. There is a whole school in Japan which, from its inception, has devoted itself to documenting all cases of people who have received treatment from the school's students, in order to make itself credible to the medical community.
Reiki works because it asserts what ancient civilizations knew all along, we are more than our physical bodies.
Mark