Does meditation have a specific effect?: a systematic experimental evaluation of a mental silence orientated definition

Meditation and its underlying ideas are increasingly popular in Western society but the practice itself has been subjected to little high quality scientific scrutiny.In this thesis I describe the outcomes of a research programme aimed at addressing this deficiency. A comprehensive systematic review and meta-analysis of the entire English-speaking database of randomised controlled trials clearly demonstrates that the extant data is characterised by a number of methodological and conceptual flaws. As a result there is currently no consistent evidence of a specific effect associated with meditation. The most fundamentally important of these flaws, I propose, is the lack of a consistent and meaningful definition of meditation.Exploring the original descriptions of the meditative experience reveals that a key feature of meditation is the experience of mental silence. Despite this, Western definitions characterise meditation as a method of relaxation, focusing of attention or cognitive modification. The poor performance of meditation in scientific studies may be explained by the fact that definitions of meditation used by Western scientists do not appear to reflect the understanding of meditation as described in the Eastern traditions from which it originated.To explore the salience of the mental silence concept I first conducted a survey of 348 meditators who used a single homogenous form of meditation called Sahaja Yoga which focuses on the experience of mental silence as its defining feature, to assess their functional health and its relationship with their meditative practices. This survey demonstrated that these meditators had not only better mental and physical health but also that a consistent relationship between health, especially mental health, and selfreported experience of mental silence existed.To investigate the possibility of whether or not this relationship was causal, a series of increasingly rigorous clinical studies were implemented. Two separate observational and case control studies of participants suffering from 1) menopausal symptoms, and 2) attention deficit hyperactivity disorder demonstrated promising outcomes. These were followed by a small but well-designed RCT of meditation for asthma, then the largest RCT of meditation for occupational stress currently in the literature. The latter two studies were specifically designed to exclude non-specific “placebo” effects. The outcomes of these studies provided strong evidence that mental silence is associated with a specific, therapeutic effect.Finally, in a heuristic physiological study mental silence meditators manifested reductions in skin temperature during meditation thereby contradicting the “reduced physiological arousal” conceptualisation of meditation. This and other data are discussed and the possibility that the mental silence experience is associated with a unique pattern of physiological activity is proposed.In conclusion, there is credible evidence to support the idea that Sahaja Yoga meditation, and hence the mental silence experience that typifies it, is associated with unique effects. The ramifications for the fields of meditation research, consciousness and religious studies and healthcare are discussed. Future studies are proposed that focus on further examination of the mental silence state and potential mechanisms by which its specific effects may occur with emphasis on immunogenetic markers and neuroimaging