A systematic study on the efficacy of various forms of meditation programs (inc mantra, transcendental, and mindfulness meditation), commissioned by the US Agency for Healthcare Research and Quality, was published in 2014.[67] After a review of 17,801 citations, the study based its conclusions on 41 randomized controlled trials with an active control, involving 2,993 participants. The assessment found "no effect or insufficient evidence of any effect of meditation programs on positive mood, attention, substance use, eating habits, sleep, and weight."
Study: http://archinte.jamanetwork.com/article.aspx?articleid=18097...