Yogaexercises and meditation-exercises have undoubtedly demonstrable effects on health.
The TM approach attempts to emphasize the Transcendental Meditation and minimize the other methods. But successes are always individually different and also dependent on the intensity and regularity of a practice and lifestyle. TM meditation is not unique, and there are also critical scientific assessments.
In this questionnaire survey the authors measured the outcome among 20 students randomly assigned to muscle relaxation training and 19 assigned to transcendental mediatation at one year (the number of respondents in each group was 13 and 16, respectively) and two and one-half years (the number of respondents was 18 and 17, respectively). At both follow-ups there were no differences between the groups in frequency of practice or satisfaction. In both groups, less than 25% reported more than moderate satisfaction, and less than 20% practices as much as once per week. Subjects' expectancies at nine weeks predicted their satisfaction and frequency of practice at two and one-half years. The authors conclude that although some subjects (15%-20%) enjoy and continue to practice transcendental meditation, it is not universally beneficial.
Peter Canter and Edzard Ernst from the University Chair of Complementary Medicine in Exeter, UK examined the available data on TM and its effects on mental performance (Wiener Klin. Wochenzeitschr, 115, 2003: 758).
However, of the more than 100 publications reviewed, only 10 met the criteria for clinical work. Of these ten, only four came to the conclusion that the performance was increased, six gave partly or completely the opposite..( Ärztezeitung 29.7.2004)
All the randomized clinical trials of TM for the control of blood pressure published to date have important methodological weaknesses and are potentially biased by the affiliation of authors to the TM organization.
* Russell, Peter H. (1977). The TM technique: a skeptics guide to the TM program. Boston: Routledge K. Paul. pp. 49–50. ISBN 0-7100-8672-5.