Meditation, an ancient mind and body practice, is used by around 18 million adults in the US.
Meditation is an ancient mind and body practice that is estimated to date back as far as 5,000 BCE. It is believed meditation originated in India, with the earliest documented records of the practice deriving from the teachings of Vedantism - an ancient Hindu philosophy.
In general, meditation involves training the mind to induce a state of consciousness that promotes a sense of serenity and increased concentration.
While meditation was traditionally practiced to induce a deeper religious and spiritual understanding, it has evolved to become a popular method of relaxation and stress reduction.
According to the National Center for Complementary and Integrative Health (NCCIH) - part of the National Institutes of Health (NIH) - meditation is practiced by around 18 million adults in the US, or 8% of the population.
Types of meditation
There are numerous forms of meditation, though most fall into four groups: concentrative, open awareness, mindfulness and guided meditation.
Concentrative meditation involves focusing the mind on a single object, such as an image, sound or breathing; Transcendental Meditation is one of the most common forms, in which the practitioner sits comfortably with their eyes closed for 20 minutes twice daily.
Open-awareness meditation, also referred to as non-directive meditation, aims to induce a sense of awareness without focusing on a specific object. Instead, the practitioner embraces all feelings and sensations that arise. Zazen - a Zen sitting practice - is a common form of open-awareness meditation.
Mindfulness is the most common form of meditation in the Western world; it combines both concentration and open awareness. In mindfulness meditation, the practitioner focuses on an object, such as sounds, bodily sensations, feelings, thoughts or breathing. Mindfulness is not as restrictive as concentrative meditation; the practitioner can focus on more than one object at a time.
Guided meditation involves the use of imagery, sounds and/or in-person guidance in order to induce a serene state of mind. Any form of meditation can fall into this category.
Meditation is commonly used to reduce anxiety and stress, but increasingly, researchers have found the benefits of meditation may have a much wider reach.
The potential benefits of meditation
Reduced brain aging and better memory
Since a key focus of meditation is to induce a tranquil state of mind, it is perhaps no surprise that researchers have found the practice yields brain benefits.
Earlier this year, a study reported by Medical News Today suggested meditation may reduce brain aging.
Studies have suggested that meditation may reduce brain aging.
The study of 100 individuals aged 24-77 - of whom 50 were meditators - found that those who engaged in meditating showed reduced gray matter loss in certain brain regions, compared with non-meditators.
Another study, published in the Journal of Alternative and Complementary Medicine in 2012, suggested that mantra-based meditation - a form of concentrative meditation in which a word, phrase or sound is repeated to prevent distracting thoughts - may help older individuals with memory loss.
The researchers, from Thomas Jefferson University Hospital in Philadelphia, PA, found that 12 minutes of mantra-based meditation daily for 8 weeks increased cerebral blood flow to the prefrontal, superior frontal and superior parietal cortices of 12 older adults with memory problems and improved their cognitive function.
While it remains unclear exactly how meditation affects the brain, researchers are getting closer to finding out.
Last year, MNT reported on a study in which researchers found individuals showed higher brain activity in brain regions associated with processing self-related thoughts, feelings and memory retrieval when they practiced Acem meditation - a form of open-awareness meditation - compared with when they were resting.
However, when the same participants practiced concentrative meditation, their brain activity in these regions was the same as when they were resting. This, according to the researchers, suggests that open-awareness meditation allows greater processing of memory and emotions than concentrative meditation.
Chronic pain - defined as pain lasting at least 12 weeks - is one of the leading causes of disability in the US, affecting around 100 million Americans. The most common types of pain include low back pain, severe headache or migraine and neck pain.
While medications such as opioids are commonly used to treat pain, studies have increasingly suggested meditation could be an effective pain reliever.
Last year, a study led by the Wake Forest Baptist Medical Center in Winston-Salem, NC, found an 8-week mindfulness-based meditation program that incorporated yoga reduced the frequency and severity of migraines; those who completed the program had 1.4 fewer migraines a month.
More recently, a study published in the Journal of Neuroscience last month - also by researchers from Wake Forest Baptist Medical Center - found that individuals who engaged in mindfulness meditation showed a 44% reduction in emotional response to physical pain and a 27% reduction in pain intensity.
Further investigation using brain imaging revealed that mindfulness meditation reduced participants' pain by activating the orbitofrontal and anterior cingulate cortex brain regions, which play a role in self-control of pain.
"Based on our findings, we believe that as little as four 20-minute daily sessions of mindfulness meditation could enhance pain treatment in a clinical setting," said lead author Fadel Zeidan.
With today's hectic lifestyles, it is no wonder so many of us have problems sleeping; around 50-70 million people in the US have some form of sleep disorder. But could meditation help? Some researchers think so.
In February this year, a study reported by MNT found that mindfulness meditation improved the sleep quality of older adults; more than half of American adults aged 55 and older have problems sleeping.
Published in JAMA Internal Medicine, the study revealed mindfulness meditation 2 hours a week for 6 weeks reduced Pittsburgh Sleep Quality Index (PSQI) scores among the adults from 10.2 to 7.4, compared with a reduction from 10.2 to only 9.1 for those who completed a sleep hygiene education program.
Better heart health
High blood pressure is a major risk factor for heart attack, stroke and heart disease. While lifestyle changes such as a healthy diet and exercise are key for reducing blood pressure, a recent study suggests meditation may also be effective.
Researchers suggest meditation may reduce blood pressure, lowering the risk for heart attack, stroke and heart disease.
Led by Dr. Robert Schneider, director of the Institute for Natural Medicine and Prevention at the Maharishi University of Management in Fairfield, IA, the study involved 48 black men and women with high blood pressure - a population who is at high risk for the condition.
Half of the participants were randomized to a Transcendental Meditation program for 16 weeks, while the other half were required to engage in lifestyle changes, such as weight reduction and exercise.
The team found that both groups showed a reduction in blood pressure as a result of an increase in expression of genes that produce telomerase - an enzyme linked to reduced blood pressure and mortality.
"The finding that telomerase gene expression is increased, and that this is associated with a reduction in blood pressure in a high-risk population, suggests that this may be a mechanism by which stress reduction improves cardiovascular health," said Dr. Schneider.
This study builds on a 2012 study conducted by Dr. Schneider and colleagues, which found that black Americans with heart disease were at 48% lower risk of all-cause mortality and death from heart attack and stroke over 5 years if they practiced Transcendental Meditation.
"Transcendental Meditation may reduce heart disease risks for both healthy people and those with diagnosed heart conditions," he commented.
With smoking being the leading cause of preventable disease and death in the US, there is more focus than ever on identifying ways to help people quit. And according to a study published in July this year, meditation could help do the trick, even for smokers who have no willpower.
Writing in Trends in Cognitive Sciences, the researchers revealed that undergraduate students who smoked demonstrated a 60% reduction in smoking in the 2 weeks after taking part in 5 hours of 30-minute mindfulness meditation sessions.
The team, led by Yi-Yuan Tang, a professor of psychological sciences at Texas Tech in Lubbock, found that this was even the case for smokers who had no willpower. On analyzing brain images of participants, they found mindfulness meditation altered their brain's self-control network, reducing cigarette smoking without them realizing.
"The students changed their smoking behavior but were not aware of it," said Prof. Tang. "When we showed the data to a participant who said they had smoked 20 cigarettes, this person checked their pocket immediately and was shocked to find 10 left."
The benefits keep coming...but there may be risks, too
According to the NCCIH, studies have also suggested that meditation may be effective for treating irritable bowel syndrome (IBS) - a condition that can cause pain and discomfort in the abdomen and lead to changes in bowel movement.
One such study, conducted in 2013 and published in the International Journal of Behavioral Medicine, found that mindfulness meditation eased the severity and symptoms of IBS over a period of 6 months.
One study found meditation may interfere with the ability to accurately recall memories.
What is more, some studies have found meditation may help treat ulcerative colitis - a form of inflammatory bowel disease than can cause ulcers and inflammation in the colon.
Last year, for example, a study published in the journal Digestion found mindfulness meditation was effective for preventing flare-ups among patients with inactive ulcerative colitis.
However, while meditation boasts a lengthy list of possible health benefits, some studies have suggested such benefits may be overstated, while some have even indicated the practice may pose health risks.
In early 2014, MNT reported on a study suggesting that, while meditation shows some health benefits, such as reductions in pain and stress, it does not offer significant benefits in other areas, such as improvement in overall well-being and mental health.
More recently, a study led by researchers found that - contrary to other studies - mindfulness meditation may have a negative impact on memory.
In the journal Psychological Science, researchers suggested mindfulness may interfere with the ability to accurately recall memories, after finding participants who engaged in mindfulness for 15 minutes were less able to accurately recall word lists than non-meditating participants.
Could greater use of meditation improve health care?
Still, given the well-documented potential health benefits of meditation, health professionals are generally in agreement that the practice does much more good than harm, with some calling for meditation to be more widely adopted.
Writing in a blog for The Huffington Post last month, Charles Francies - author of the book, "Mindfulness Meditation Made Simple: Your Guide to Finding True Inner Peace," - argues that more people should use meditation to improve their overall health, which, in turn, could have a positive impact on health care services.
"The recent rise in popularity of mindfulness meditation is helping people live healthier lives by helping them cope with stress in ways that don't harm the body and mind," he said.
"This will lower the demand for health care services, and exert downward pressure on costs, and upward pressure on quality. With mindfulness meditation we can take back control of our health care system, and keep health care affordable and accessible to everyone."
Francis's argument is supported by a study published in PLOS One in October. Researchers found that most health care costs in the US are a result of disorders related to stress, such as anxiety and depression, with such conditions costing around $80 billion annually.
Lead study author James Stahl, of Dartmouth-Hitchcock Medical Center in Lebanon, NH, and colleagues compared the medical data of more than 4,400 individuals who took part in stress-reducing meditation programs and other relaxation techniques with that of 13,150 people who did not.
The team found that those who engaged in relaxation practices used significantly fewer health services than those who did not engage in such practices.
"We have shown in the past that it works in the laboratory and on the level of individual physiology, and now we can see that when you make people well, they do not want to use health care so much," said Stahl.
"Just like fluorinating your water or vaccinating yourself, these are ways of keeping you healthy with, from a public health perspective, minimal investment."
Last year, Dr. Schneider wrote an article for MNT that provides further information on how meditation may benefit the mind and body.