At its core this is a question about belief, not about Reiki. If a client conviction that the treatment works tracks with how their body responds, that points toward expectancy. And expectancy is exactly what blinded studies are built to test.
The cleaner way to ask it is to strip out prior knowledge entirely. When someone receives Reiki without being told what it is, or without knowing whether they are getting the real thing or a sham version, their belief can no longer drive the result. That is the logic of blinding, and it is how the field actually probes whether anything beyond expectation is at work.
The results from that design are telling. In blinded trials, participants often cannot distinguish real Reiki from sham Reiki, and both tend to outperform doing nothing while matching each other. People report better well-being after either version compared to no treatment at all. The most parsimonious reading is that the benefit travels with relaxation, attention, and expectation rather than with any Reiki-specific action.
So belief intensity plausibly does relate to physiological outcomes, but not because stronger belief unlocks more energy. Stronger expectation can amplify a placebo response, lower arousal, and produce real, measurable shifts such as slower breathing or reduced reported stress. Those changes are genuine. They are also the kind of effect that expectation produces across many comforting interventions, not a fingerprint of Reiki itself.
This is worth stating plainly so it is not misread. A placebo response is not nothing. Feeling calmer, sleeping a little easier, or hurting a little less because one expected to is a real outcome that can matter to a person. The honest claim is about its source, which the evidence places in expectancy and relaxation, not in a transferred energy.
For the specific scenario of clients given no prior knowledge, the expected pattern is muted effects, since the belief that usually powers the response has been removed. That outcome, rather than undercutting the experience, simply locates it accurately. The comfort many people feel is worth taking seriously, and so is the reason behind it, which sits in the mind and the body responding to calm rather than in anything Reiki delivers on its own. Serious health concerns still belong with a clinician.