Important sections:

>As early as 1976, Arnold Lazarus, one of the forefathers of cognitive behavioral therapy, raised concerns about transcendental meditation, the mantra-based practice then in vogue. “When used indiscriminately,” he warned, “the procedure can precipitate serious psychiatric problems such as depression, agitation, and even schizophrenic decompensation.” Lazarus had by then treated a number of “agitated, restive” patients whose symptoms seemed to worsen after meditating. He came to believe that the practice, while beneficial for many, was likely harmful to some.

>One case study, from 2007, documented a twenty-four-year-old male patient who had slipped into “a short-lasting acute psychotic state” during “an unguided and intense” meditation session. He was referred to clinicians following the onset of “an acute sensation of being mentally split.” He saw vivid colors, hallucinated, and was overcome with severe anxiety. At the height of the episode, he was tormented by “delusional convictions that he had caused the end of the world” and talked of suicide. The man had experienced one previous hypomanic episode and had a history of untreated depression. The authors posited that “meditation can act as a stressor in vulnerable patients.”

>Even as academic interest in meditation has mounted, with hundreds of new papers published every year, the question of adverse effects has received little attention. Most studies don’t monitor for negative reactions, relying instead on participants to report them spontaneously. But the research that does exist is not reassuring. More than fifty published studies have documented meditation-induced mental health problems, including mania, dissociation, and psychosis. In 2012, leading meditation researchers in the United Kingdom published a set of guidelines for meditation instructors, noting “risks for participants,” including depression, traumatic flashbacks, and increased suicidal ideation. Four years later, the U.S. National Institutes of Health cautioned that “meditation could cause or worsen symptoms in people with certain psychiatric problems.” Jeffrey Lieberman, the former head of the American Psychiatric Association, told me he’d seen this in his own practice. “The clinical phenomenon is real,” he said. “There’s no question about it.”

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>Britton and her team began visiting retreats, talking to the people who ran them, and asking about the difficulties they’d seen. “Every meditation center we went to had at least a dozen horror stories,” she said. Psychotic breaks and cognitive impairments were common; they were often temporary but sometimes lasted years. “Practicing letting go of concepts,” one meditator told Britton, “was sabotaging my mind’s ability to lay down new memories and reinforce old memories of simple things, like what words mean, what colors mean.” Meditators also reported diminished emotions, both negative and positive. “I had two young children,” another meditator said. “I couldn’t feel anything about them. I went through all the routines, you know: the bedtime routine, getting them ready and kissing them and all of that stuff, but there was no emotional connection. It was like I was dead.”

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There seems to be something of a catch 22 here. Normal people generally don't meditate. Some people meditate shallowly, and experience light effects. But if you're the kind of person who is interested in meditating for 10 hours a day, either to run away from something or go on some mental journey, then you lose your mind and either become a basket case or a yogi.