"The available English-language literature of Reiki was reviewed, specifically for peer-reviewed clinical studies with more than 20 participants in the Reiki treatment arm, controlling for a placebo effect. Of the 13 suitable studies, 8 demonstrated Reiki being more effective than placebo, 4 found no difference but had questionable statistical resolving power, and only one provided clear evidence for not providing benefit. Viewed collectively, these studies provide reasonably strong support for Reiki being more effective than placebo. From the information currently available, Reiki is a safe and gentle “complementary” therapy that activates the parasympathetic nervous system to heal body and mind. It has potential for broader use in management of chronic health conditions, and possibly in postoperative recovery. Research is needed to optimize the delivery of Reiki."

McManus DE. Reiki Is Better Than Placebo and Has Broad Potential as a Complementary Health Therapy. J Evid Based Complementary Altern Med. 2017 Oct;22(4):1051-1057. doi: 10.1177/2156587217728644. Epub 2017 Sep 5. PMID: 28874060; PMCID: PMC5871310.