Zen Meditation vs. Transcendental Meditation: How They Differ, and What the Evidence Shows
zen meditation vs transcendental meditation
Zen meditation is a family of seated practices within Zen Buddhism, including shikantaza, or 'just sitting'. Transcendental Meditation (TM) is a standardized mantra technique from the Vedic tradition of India. Here is where each comes from, how they differ, and what the research shows.
Zen meditation, most often zazen (seated practice), belongs to Zen Buddhism and includes shikantaza, which is commonly translated as 'just sitting'. Transcendental Meditation (TM) is a standardized mantra technique from the Vedic tradition of India. Zen is a family of practices within a Buddhist tradition; TM is a single assigned technique. TM has been tested in several controlled trials, while we did not locate controlled trials of zazen or shikantaza as such.
Where Zen comes from
Zen is a school of Buddhism. Eihei Dōgen (1200 to 1253) is described as the founder of the Soto Zen Buddhist school in Japan, according to a 2025 paper by S. P. Cooper in The American Journal of Psychoanalysis. Cooper describes shikantaza, 'just sitting, only sitting', as the expressive practice that Dōgen promoted, and contrasts it with other, more instrumental forms of contemplative practice. That paper is written from a psychoanalytic perspective, so it is a secondary account of Dōgen's teaching and not a historical study of it.
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One of the early scientific studies of zazen in our sources is an electroencephalographic study by A. Kasamatsu and T. Hirai, published in 1966 in Psychiatry and Clinical Neurosciences. We checked the title and publication record of that paper, not its full text, so we cite it as an early point in the research line and do not report its findings.
Where Transcendental Meditation comes from
A 2024 meta-analysis by D. W. Orme-Johnson and colleagues describes TM as a standardized meditation technique from the Vedic tradition of India, brought to the West by Maharishi Mahesh Yogi in the 1950s. In that description, the mantras are assigned by TM instructors, and the technique is described as effortless, a process in which the mind is automatically drawn inward toward a state of restful alertness. The same paper lists three of its five authors with affiliations to Maharishi International University or a TM-affiliated organization, a point the evidence section returns to.
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Where they overlap
Both are described as ways of settling the mind and reducing reactivity. The 2024 PTSD meta-analysis describes TM as a state of restful alertness, and a 2026 neuroscience paper describes zazen as aiming to perceive thoughts without judgment by attentively focusing on the present. The shared ground we could locate in the research comes from the taxonomy that Travis and Shear (2010) proposed. Their framework sorts meditations into focused attention, which keeps attention on an object; open monitoring, which keeps attention on the process of monitoring experience; and automatic self-transcending, a third category they proposed. In their analysis, Buddhist meditations fall under focused attention and open monitoring, and Vedic meditations fall under open monitoring and automatic self-transcending. So the two traditions share the open-monitoring category in that framework, even though the 2024 meta-analysis places TM itself under automatic self-transcending.
Where they genuinely differ
Three differences stand out in the sources we checked. The first is the form of practice. Zen practice spans several forms, and shikantaza is one of them, which Cooper's paper sets apart from more instrumental forms. TM uses one assigned mantra. The second is standardization. TM is described as a standardized technique taught by its instructors, whereas Cooper's paper points out that different contemplative practices reflect and express the underlying assumptions, guiding principles and goals of different traditions. The third is the research base, which is uneven. TM has been tested in randomized trials on blood pressure and cognition, and a 2024 meta-analysis covers PTSD studies, while we did not locate controlled trials of zazen or shikantaza as defined practices. The table lays these side by side with two further points.
| Zen meditation (zazen) | Transcendental Meditation (TM) | |
|---|---|---|
| Origin | Zen Buddhism; Eihei Dōgen (1200 to 1253) is described as founder of the Soto school in Japan | Vedic tradition of India; brought to the West by Maharishi Mahesh Yogi in the 1950s |
| Core practice | Zazen, seated practice, including shikantaza ('just sitting') | Repeating an assigned mantra, described as effortless |
| Standardization | Forms reflect each tradition's assumptions and goals, according to Cooper (2025) | Described as a standardized technique taught by TM instructors |
| Place in the Travis and Shear (2010) framework | Buddhist meditations fall under focused attention and open monitoring | The 2024 meta-analysis places TM under automatic self-transcending |
| Controlled trials located | None located for zazen or shikantaza as such; an early EEG study (1966) and a 2026 fMRI study of experienced monks | Randomized trials on blood pressure and cognition, with contested quality; a 2024 PTSD meta-analysis with several TM-affiliated authors |
Drawn from the sources listed below. This is not a full systematic review of either practice.
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What the evidence actually says
The blood pressure reviews disagree. Anderson, Liu and Kryscio (2008) pooled nine randomized controlled trials of TM and reported average reductions compared with control of about 4.7 mmHg systolic and 3.2 mmHg diastolic. The authors called these clinically meaningful changes and framed TM's effect as a potential one. Canter and Ernst (2004) reviewed the randomized trials of TM and blood pressure and concluded that there is insufficient good-quality evidence to conclude whether or not TM has a cumulative positive effect on blood pressure. They noted important methodological weaknesses in those trials, and that the trials could be biased by the authors' affiliation with the TM organization.
On cognition, Canter and Ernst (2003) reviewed ten randomized trials. Four reported large positive effects, four were negative and two were largely negative. All four positive trials recruited people who were already favourably disposed toward TM and used passive control procedures, which the authors suggested could produce an expectation effect. They concluded that the randomized evidence does not support a specific, cumulative effect of TM on cognitive function.
A 2024 meta-analysis by Orme-Johnson, Barnes, Rees, Tobin and Walton covered 61 studies of meditation for PTSD and reported a larger pooled effect for TM than for the other categories: a Hedges' g of -1.13 for TM, against roughly -0.52 to -0.66 for the others. The paper reports that no study recorded serious side effects and that the research received no external funding. Three of its five authors list Maharishi International University or a TM-affiliated organization, and the authors call for a multisite trial. The affiliation question raised in the 2004 review applies to this paper as well, and readers can weigh it directly.
For Zen practice, the evidence we found is neuroscientific rather than clinical. Kasamatsu and Hirai (1966) is an early EEG study of zazen. Osaka and colleagues (2026) used fMRI to compare experienced Zen monks, averaging about 7.5 years of practice, with a control group without meditation background, during a Stroop cognitive conflict task. They reported that the monks showed improved responses and cognitive control, with less conflict-related activity in lateral and medial prefrontal cortex. Those findings describe brain activity during a task. They do not show that zazen improves blood pressure, stress or trauma symptoms.
Put plainly: for TM there are randomized trials of contested quality on blood pressure and cognition, and a PTSD meta-analysis on which three of five authors list TM-affiliated institutions. For zazen and shikantaza, in the sources we checked, we did not locate controlled trials of the practice itself, and we did not locate a trial comparing the two directly. Intensive practice in either tradition can bring difficult experiences to the surface, including on long retreats, and a qualified clinician is the right person to speak with if that happens.
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Choosing between them, honestly
These are tendencies, not verdicts. A person who wants a defined technique with a set mantra, taught by instructors, may find TM's shape easier to start with, and may want to weigh the affiliation questions above when reading its research. A person drawn to a tradition with its own history, teachers and forms, including teacher-led sitting, or to practices that rest in open awareness rather than a single object, may find Zen's range closer to what they want. Neither is established as better for stress, blood pressure or any other outcome, and we did not locate a trial that compares them directly.
If you are having thoughts of harming yourself, contact local emergency services or a crisis line, such as 988 in the US.
How to evaluate any teacher, book, program or tool for this
Ask who wrote the research and whether they also teach or sell the practice, since the 2004 and 2024 examples above illustrate the question. Ask whether the source names its tradition and the lineage of its teachers, and how those teachers were trained. Ask whether it separates what a tradition teaches from what has been tested, and whether it says what it does not know. And ask what it offers when a practice brings up something hard. A program that answers these plainly is easier to check than one that does not.
Where IX Coach fits
IX Coach is an AI coaching platform designed to help people notice what is driving them in a given moment and reflect on it. It does not teach TM or Zen, it is not a teacher or part of either lineage, and it is not therapy. It is not a crisis service and does not detect a crisis; if what comes up feels heavy, a qualified clinician is the right person to talk to.
Research
- Canter, P. H., & Ernst, E., (2004), Insufficient evidence to conclude whether or not Transcendental Meditation decreases blood pressure: results of a systematic review of randomized clinical trials, Journal of Hypertension, 22(11), 2049-2054 — Systematic review of randomized trials of TM and blood pressure. Concludes evidence is insufficient, notes methodological weaknesses, and notes the possibility of bias from author affiliation with the TM organization.
- Anderson, J. W., Liu, C., & Kryscio, R. J., (2008), Blood pressure response to transcendental meditation: a meta-analysis, American Journal of Hypertension, 21(3) — Meta-analysis of nine randomized controlled trials; pooled reductions of about 4.7 mmHg systolic and 3.2 mmHg diastolic against control. The authors framed the effect as a potential one. The positive side of the blood pressure debate, read against the 2004 review.
- Canter, P. H., & Ernst, E., (2003), The cumulative effects of Transcendental Meditation on cognitive function: a systematic review of randomised controlled trials, Wiener Klinische Wochenschrift, 115 — Systematic review of ten randomized trials of TM and cognition. Four positive, four negative, two largely negative. The authors link the positive trials to participant selection and passive controls, and conclude the evidence does not support a specific cumulative effect.
- Orme-Johnson, D. W., Barnes, V. A., Rees, B., Tobin, J., & Walton, K. G., (2024), Effectiveness of meditation techniques in treating post-traumatic stress disorder: a systematic review and meta-analysis, Medicina, 60(12), 2050 — Meta-analysis of 61 PTSD studies; larger pooled effect for TM than for other meditation groups. Full text also describes TM as a standardized, Vedic-derived technique brought to the West in the 1950s, with mantras assigned by instructors, and lists author affiliations with Maharishi International University or TM organizations. Three of its five authors list TM-affiliated institutions, so the paper is worth reading alongside the 2004 review.
- Travis, F., & Shear, J., (2010), Focused attention, open monitoring and automatic self-transcending: categories to organize meditations from Vedic, Buddhist and Chinese traditions, Consciousness and Cognition — Proposes automatic self-transcending as a third meditation category beside focused attention and open monitoring; places Buddhist meditations in the first two and Vedic meditations in the last two. Used here for the taxonomy only, not for any claim about outcomes.
- Cooper, S. P., (2025), Thinking's bad rap: the uses and misuses of Zen Buddhist meditation in psychoanalytic therapy, The American Journal of Psychoanalysis, 85(1) — Describes shikantaza ('just sitting, only sitting') as the expressive Soto Zen practice promulgated by Eihei Dōgen (1200-1253), founder of the Soto school in Japan, and distinguishes it from instrumental and quietist practices. Written from a psychoanalytic perspective; we checked the abstract only.
- Kasamatsu, A., & Hirai, T., (1966), An electroencephalographic study on the Zen meditation (Zazen), Psychiatry and Clinical Neurosciences — An early EEG study of zazen. We checked the title and publication record only, so this is cited to show the research line exists, not for its findings.
- Osaka, N., Minamoto, T., Yaoi, K., Azuma, M., & Osaka, M., (2026), Neural bases of consciousness in Zen meditation: central executive and default mode networks during cognitive conflict, Frontiers in Psychology — fMRI comparison of Zen monks (average about 7.5 years of practice) with a control group during a Stroop conflict task. Reports improved responses and cognitive control, and less conflict-related prefrontal activity, in the monks. Describes brain activity, not clinical outcomes.
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