I see lots of articles touting the benefits of meditation. But what are the bad things about it? Maybe if a person has to make quick decisions, meditation would not be a good thing? This could be similar to a paridigm of "Thinking Fast, Thinking Slow" by Kahneman.
The adverse effects of meditation as reported in scientific studies are as follows:
- relaxation-induced anxiety and panic
- paradoxical increases in tension
- less motivation in life
- impaired reality testing
- confusion and disorientation
- feeling 'spaced out'
- increased negativity
- being more judgmental
- feeling addicted to meditation
- uncomfortable kinaesthetic sensations
- mild dissociation
- feelings of guilt
- psychosis-like symptoms
- destructive behavior
- suicidal feelings
- increased false-memory susceptibility
Also, anecdotal evidence suggests that meditation can worsen symptoms of some psychiatric problems.
Study from 1992: http://www.ncbi.nlm.nih.gov/pubmed/1428622
Adverse effects of meditation: a preliminary investigation of long-term meditators, by Shapiro DH Jr.
Department of Psychiatry and Human Behavior, California College of Medicine, University of California, Irvine.
Adverse effects of meditation were assessed in twenty-seven long term meditators (average 4.27 years) both retrospectively (time one) and prospectively at one month (time two) and six months (time three) following a meditation retreat. At both time one and time three subjects reported significantly more positive effects than negative from meditation. However, of the twenty-seven subjects, seventeen (62.9%) reported at least one adverse effect, and two (7.4%) suffered profound adverse effects. When subjects at time one were divided into three groups based on length of practice (16.7 months; 47.1 months; 105 months) there were no significant differences in adverse effects. How the data should be interpreted, and their implications both for the clinical and psychotherapeutic use of meditation as a relaxation/self-control strategy, and as a technique for facilitating personal and spiritual growth, are discussed. Limitations of the study and suggestions for future research are also offered.
Meta-analysis from 2000:
Meditation: concepts, effects and uses in therapy by Alberto Perez-De-Albeniz and Jeremy Holmes
International Journal of Psychotherapy, Mar2000, Vol. 5 Issue 1, p49, 10p
Abstract: This article reviews 75 scientific selected articles in the field of meditation, including Transcendental Meditation among others. It summarizes definitions of meditation, psychological and physiological changes, and negative side-effects encountered by 62.9% of meditators studied. While the authors did not restrict their study to TM, the side-effects reported were similar to those found in the "German Study" of Transcendental Meditators: relaxation-induced anxiety and panic; paradoxical increases in tension; less motivation in life; boredom; pain; impaired reality testing; confusion and disorientation; feeling 'spaced out'; depression; increased negativity; being more judgmental; feeling addicted to meditation; uncomfortable kinaesthetic sensations; mild dissociation; feelings of guilt; psychosis-like symptoms; grandiosity; elation; destructive behavior; suicidal feelings; defenselessness; fear; anger; apprehension; and despair.
New study shows increase in cortisol reactivity (a biological marker of stress): http://www.ncbi.nlm.nih.gov/pubmed/24767614
The present study provides an initial indication that brief mindfulness meditation training buffers self-reported psychological stress reactivity, but also increases cortisol reactivity to social evaluative stress. This pattern may indicate that initially brief mindfulness meditation training fosters greater active coping efforts, resulting in reduced psychological stress appraisals and greater cortisol reactivity during social evaluative stressors.
Another new study shows increased susceptibility to false memories:
Increased False-Memory Susceptibility After Mindfulness Meditation by Brent M. Wilson, Laura Mickes, Stephanie Stolarz-Fantino, Matthew Evrard and Edmund Fantino in Psychololgical Science
The effect of mindfulness meditation on false-memory susceptibility was examined in three experiments. Because mindfulness meditation encourages judgment-free thoughts and feelings, we predicted that participants in the mindfulness condition would be especially likely to form false memories. In two experiments, participants were randomly assigned to either a mindfulness induction, in which they were instructed to focus attention on their breathing, or a mind-wandering induction, in which they were instructed to think about whatever came to mind. The overall number of words from the Deese-Roediger-McDermott paradigm that were correctly recalled did not differ between conditions. However, participants in the mindfulness condition were significantly more likely to report critical nonstudied items than participants in the control condition. In a third experiment, which tested recognition and used a reality-monitoring paradigm, participants had reduced reality-monitoring accuracy after completing the mindfulness induction. These results demonstrate a potential unintended consequence of mindfulness meditation in which memories become less reliable.
Official recommendations in the US: http://nccam.nih.gov/health/meditation/overview.htm#sideeffects
Side Effects and Risks
Meditation is considered to be safe for healthy people. There have been rare reports that meditation could cause or worsen symptoms in people who have certain psychiatric problems, but this question has not been fully researched. People with physical limitations may not be able to participate in 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.