Previous chapter: 6.2 Vipassana Meditation
6.3 Examples of the physiological and biochemical effects of meditation:
The processes which occur at the cell level during conditioning have been described above. Physiological correspondence is also found for the observed psychological changes resulting from meditation. It is possible to draw on the numerous investigations of people who practise Transcendental Meditation, who - at least as far as inner tranquillity is concerned – achieve comparable psychological results to those who apply Vipassana Meditation (quoted from ref. 10):
- In an investigation of 14 meditating and 16 control persons, more rapid physiological habituation of the GSR (galvanic skin reaction) to irregularly presented stress stimuli, a lower number of multiple GSR per stimulus and a lower number of spontaneous skin resistance fluctuations were observed for the meditating group. This was interpreted as an indication of more efficient neurological information processing and greater physiological stress stability.
- Stress releases the hormones CRF (corticotrophin releasing factor) and AVP (arginine vasopressin) from specialised nerve cells deep within the brain. These hormones activate the release of stress hormones (glucocorticoids), which prepare the body for defence. Experiments with rats demonstrated that when a stress-inducing stimulus was repeated, these cells change from producing the more strongly activating CRF to the weaker AVP, so that the reaction to stress gradually decreases (habituation). Analogously, the average fivefold increase on the original value of AVP secretion for people who practise meditation over long periods can be interpreted as a weakened reaction to stress.
- Various hormonal changes have been observed, including reduced cortisol levels in blood plasma and urine, reduced TSH values and raised dehydro-epiandrosterone-sulphate values (DHEA, DHS), particularly among those who have practised meditation for many months. They are interpreted by the authors as evidence for greater physiological stress stability (cortisol and TSH reduction) and retarding of the age-induced reduction in DHEA/DHS secretion in the adrenal gland cortex, as the DHS values corresponded to control persons who were about 5 - 10 years younger.
In a review article on meditation (ref. 11), numerous studies on the physiological effects of meditation are cited. Summarising the results, meditation beginners display physiological reactions which correspond to physical relaxation. People with longer experience of meditation (12 - 18 months) show more permanent hormonal and metabolic changes.
The positive effects of mindfulness meditation on health have also been proven for German patients with chronic physical, psychological or psychosomatic complaints (ref. 12). The effects were determined with standardised instruments. Moderate to large effects were found in the reduction of psychological stress, as well as an improvement in well-being and the quality of life. In addition, the body-orientated approach proved to complement psychotherapy positively.
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