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October 21, 2026
Kansha shite · Be grateful
145 Studies Tested Gratitude, a Reiki Precept. The Effect Is Small but Real.
Nearly 25,000 people, 145 studies, two decades of research, one preregistered analysis. Gratitude practices do raise wellbeing. Modestly, reliably, and with one open question the researchers could not answer.
Kansha shite, be grateful, is the third of the five precepts. It sits at the heart of Reiki self-practice.
The study
Every gratitude trial they could find, weighed together
A meta-analysis does not run a new experiment. It gathers every existing one that meets its standards and combines their results into a single estimate. This one was preregistered, meaning the researchers declared their methods before they saw the data, and it took in every eligible study published between 2003 and May 2024.
The interventions were the familiar ones: gratitude journals, gratitude letters, lists of blessings. The outcomes were the familiar ones too: life satisfaction, positive mood, happiness. The novel question was whether it all worked the same way in every culture.
- Design
- Preregistered three-level meta-analysis
- Included
- 145 papers, 163 samples, 727 effect sizes
- Period
- Studies published 2003 to 2024
- Published in
- PNAS, July 2025
What they found
What the review established
The effect is real, and small
Across everything, gratitude practices raised wellbeing by a Hedges’ g of 0.19, with a confidence interval of 0.15 to 0.22. That is comfortably above zero and comfortably below what most people imagine when they hear that gratitude is good for you.
Country matters, and nobody knows why
The differences between countries were statistically significant. But when the researchers tested whether individualism, wealth, or other cultural measures could explain them, none did. The variation is real and, for now, unexplained.
Method matters
Three things shaped the size of the effect: which outcome was measured, which type of practice was used, and whether participants were properly randomised. Combining more than one practice produced larger effects than any single one.
It survived the bias check
Studies with positive results are more likely to be published, which can inflate a meta-analysis. The researchers modelled a worst case and found the effect fell to 0.07, still above zero. Small, but not an illusion.
Small is not nothing. A reliable effect of this size, across this many people, is more than most everyday practices can show for themselves.
The open question
The effect was not the same in every country, and no one knows why
Only countries with enough studies could be assessed on their own. In five, the effect was clear. In five others it was not, though for most of those the evidence was thin rather than negative.
A clear effect
No clear effect, or too few studies to say
The researchers tested individualism, wealth and other cultural measures as explanations for the difference. None of them held up. The variation is real, and for now it is unexplained.
Why the Japanese result matters for precept practice
Every intervention in this review was a task: write the letter, count the blessings, keep the journal. Every outcome was a score on a wellbeing scale designed in the West. Japan is the country the precepts come from, and it is one of the places where that pairing produced nothing the review could measure with confidence.
That could mean gratitude does less in Japan. It could equally mean that gratitude in Japan is not well captured by writing exercises and happiness questionnaires. A separate Japanese study, covered elsewhere in this series, found gratitude tied to growth, closeness and purpose rather than life satisfaction. Kansha shite was never framed as a task with a score. The research may simply not have been looking in the right place.
Read this part too
Limitations
A meta-analysis inherits every weakness of the studies inside it.
- Small means small. A g of 0.19 is a modest shift. It is not the transformation that popular writing on gratitude often implies.
- The country results rest on few studies each. The overall figure draws on 163 samples. Any single country draws on a handful, which makes its estimate wide and uncertain.
- Not significant is not the same as no effect. For Japan in particular, the honest reading is that the evidence was too thin to tell, not that gratitude failed.
- Mostly Western data. Twenty-eight countries sounds broad, but the bulk of the participants still came from a few wealthy Western nations.
- Self-report throughout. Wellbeing was measured by asking people, which is fine, but it means the whole review rests on questionnaires.
- Short practices, short follow-up. Most trials ran for days or weeks and measured straight afterwards. Long-term effects are largely untested.
- Tasks, not dispositions. This is a review of gratitude exercises. It says little about people who simply live gratefully without doing exercises at all.
The research
Choi, H., Cha, Y., McCullough, M. E., Coles, N. A., & Oishi, S. (2025). A meta-analysis of the effectiveness of gratitude interventions on well-being across cultures. Proceedings of the National Academy of Sciences, 122(28), e2425193122.
This is research into gratitude, not into Reiki, Reiki treatments or Reiki training. It is included here because gratitude is one of the five precepts.
For today only, be grateful.
Not because a study said so, and not in a way a study would necessarily know how to measure.
