Subjects
18 healthy male volunteers participated in this study They were between 20 and
52 years (mean ± S.D. was 34.1 ± 8.1 years), and they had 5-25 years
experience of the meditation procedure (mean ± S.D. was 10.1 ± 6.2 years). The
study was explained to the subjects and their signed informed consent was
taken, according to the ethics laid down by the Indian Council of Medical
Research New Delhi.
Meditation The Brahmakumaris Raja (= Raj) yoga
meditation (BK) has spread from the organisation"s headquarters at Mount Abu
(Rajasthan, India) throughout India, and to other countries as well. During
meditation, subjects sit in a comfortable posture with their eyes open, and
with gaze fixed on a meaningful symbol (a light). At the same time they
actively think positive thoughts about a Universal force pervading all over,
as light and peace (Easy Raj Yoga, 1981).
Test sessions Each subject was assessed in two
types of session involving either a meditation period (with targeted thinking)
or a non-meditation period (with random thinking). Each type of session was
repeated thrice on different days, but at the same time of day.
During the recording session the subject sat in a comfortable chair in a
dimly-lit, air conditioned and sound-attenuated cabin. Subjects were observed
throughout on a closed-circuit television. Each session was of 36 min
duration, of which 24 min was spent in meditation (with eyes open) preceded
and followed by 6-min periods of relaxation, also with eyes open. These
meditation sessions were repeated thrice by each subject on different days. In
addition, there were also three non-meditation ("control") sessions, which
were similar in design, except that the period corresponding to the 24 min of
meditation was spent sitting relaxed, without targeted thinking. Data acquisition and analysis
Recordings were made on Grass model 78D polygraph. EKG was recorded using a
standard limb lead II configuration. Skin resistance (SR) was recorded with
AgCl disc electrodes placed approx. 4 cm apart on the palmar surface of the
right hand. Electrode gel CSR (Technocarta, Hyderabad, India) was used, and a
constant current of 10 µA was passed. Finger plethysmogram amplitude was
recorded with a photo-cell transducer kept at the base of the right thumb
nail. Respiration was recorded via a rubber stethograph connected through a
pressure transducer.
In addition, the EEG was recorded from electrodes placed at F3, F4, 01 and 02,
referenced to the contralateral earlobe. Also, EOG and chin EMG were recorded
as is usual for sleep-stage scoring (Rechtschaffen and Kales, 1968). This
allowed any sleep episodes to he detected and excluded from the analysed data.
The SR values were sampled at 20s intervals from the continuously acquired
record. The heart rate was obtained by counting the number of QRS complexes
occurring in successive epochs of 40s periods analysed throughout. The
respiratory rate was calculated from the record by counting the breath cycles
in successive 40s epochs continuously. 20s or its multiple (i.e., 40 s) time
epochs were used while calculating SR, heart rate and respiratory rate to make
it feasible to correlate these data with that of EEG acquired simultaneously
and subjected to computerized power spectral analysis in 20s epochs. For the
present group of meditators the EEG data have been presented elsewhere (Kulkarni
et al., 1988), and have not been reiterated here as no interesting
correlations emerged between autonomic and EEG changes. The finger
plethysmogram amplitude was calculated from measurement on 20 plethysmogram
waves picked up randomly in each 6-min period.
Data analysis was done in two ways. viz., (1). For the group as a whole two
statistical tests were used. (a), A two-factor (Factor A, meditation vs.
non-meditation and Factor B, pre vs. during) ANOVA was carried out to assess
the effects of both factors, as well as the interaction of
Table -1 : Heart rate in different conditions of
the meditation and non-meditation sessions of the 18 subjects M, meditation
period; pre-M, period preceding Meditation; NM, non-meditation period; n,
number of values averaged per subject; pre-NM, period preceding
Non-meditation; n.s., non significant.
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