certain meditative practices involving physical movement. Individuals with existing mental or physical health conditions should speak with their health care providers prior to starting a meditative practice and make their meditation instructor aware of their condition.Both positive rewards and potential benefits of meditation have been noted in academic literature. Adverse effects have been reported,[37] and may, in some cases, be the result of "improper use of meditation".[38] The NIH advises prospective meditators to "ask about the training and experience of the meditation instructor... [they] are considering."Kundalini syndrome is a claimed adverse effect from practicing Kundalini Yoga.As with any practice, meditation may also be used to avoid facing ongoing problems or emerging crises in the meditator's life. In such situations, it may be helpful to apply mindful attitudes acquired in meditation while actively engaging with current problems. According to the NIH, meditation should not be used as a replacement for conventional health care or as a reason to postpone seeing a doctor.[36]NCCAM studiesA comparison of the effect of various meditation techniques on systolic blood pressure.In June, 2007 the United States National Center for Complementary and Alternative Medicine (NCCAM) published an independent, peer-reviewed, meta-analysis of the state of meditation research, conducted by researchers at the University of Alberta Evidence-based Practice Center. The report reviewed 813 studies involving five broad categories of meditation: mantra meditation, mindfulness meditation, yoga, Tai Chi, and Qi Gong, and included all studies on adults through September 2005, with a particular focus on research pertaining to hypertension, cardiovascular disease, and substance abuse.The report concluded, "Scientific research on meditation practices does not appear to have a common theoretical perspective and is characterized by poor methodological quality. Firm conclusions on the effects of meditation practices in healthcare cannot be drawn based on the available evidence. Future research on meditation practices must be more rigorous in the design and execution of studies and in the analysis and reporting of results." (p. 6) It noted that there is no theoretical explanation of health effects from meditation common to all meditation techniques.A further analysis of this data set in 2008 reaffirmed the weaknesses of the research, finding that "Most clinical trials on meditation practices are generally characterized by poor methodological quality with significant threats to validity in every major quality domain assessed". This was the conclusion despite a statistically significant increase in quality of all reviewed meditation research, in general, over time between 1956-2005. Of the 400 clinical studies, 10% were found to be good quality. A call was made for rigorous study of meditation. These authors also noted that this finding is not unique to the area of meditation research and that the quality of reporting is a frequent problem in other areas of complementary and alternative medicine (CAM) research and related therapy research domains.In 2006 NCCAM revised their definition of meditation, emphasizing the experience of the suspension of thought activity". This definition led to the possibility of comparing mental silence oriented meditation with resting alone and studies have found significant physiological differences between the two. It has been found that all approaches to meditation