At the simplest, most obvious level, it appears that Reiki treatment helps lessen the impact of stress, releasing tension from the entire system. Not only does the person move toward his or her own unique balance in body, mind and spirit, but also, depending on the level of physical health when Reiki begins, the body's own healing mechanisms often begin functioning more effectively.
What is Reiki doing?
How exactly does Reiki release tension and help the body heal? That question has yet to be answered. Although there is increasing research evidence documenting the effects of Reiki (such as lowered heart rate, blood pressure, and stress hormones; increased immune strength), we have only broad theories as to what causes these effects or the pathways through which the healing occurs.
The multileveled, rapid response to Reiki suggests a complex process that engages many body systems, simultaneously or in quick succession, shifting the body from domination by the "fight or flight" (stress) response to the relaxation response, and supporting the body's own healing mechanisms. (For more information about the relaxation response, see the Mind-Body Therapies section.) Some researchers theorize that Reiki's physical, mental, emotional, and spiritual healing effect is triggered on a subphysical level, perhaps in what science refers to as the biofield.