Reiki (pronounced raykey) is a form of “energy healing,” essentially the Asian version of faith healing or laying on of hands. Practitioners believe they are transferring life energy to the patient, increasing their well-being. The practice is popular among nurses, and in fact is practiced by nurses at my own institution (Yale).
From reiki.org, we get this description:
Reiki is a Japanese technique for stress reduction and relaxation that also promotes healing. It is administered by “laying on hands” and is based on the idea that an unseen “life force energy” flows through us and is what causes us to be alive. If one’s “life force energy” is low, then we are more likely to get sick or feel stress, and if it is high, we are more capable of being happy and healthy.
Reiki is therefore a form of vitalism – the pre-scientific belief that some spiritual energy animates the living, and is what separates living things from non-living things. The notion of vitalism was always an intellectual place-holder, responsible for whatever aspects of biology were not currently understood. But as science progressed, eventually we figured out all of the basic functions of life and there was simply nothing left for the vital force to do. It therefore faded from scientific thinking. We can add to that the fact that no one has been able to provide positive evidence for the existence of a vital force – it remains entirely unknown to science.