Can the value of meditation be measured? The scientific evidence at this point is mixed. But there is unequivocal endorsement from many practitioners. How does it all add up?
Does it work: The scientific evidence
Starting with the science, the most comprehensive research study to date is a meta-analysis which reviewed the results of 18,753 meditation studies. Of all these studies, only 47 were determined to be valid, i.e., based on reliable scientific method. M. Goyal et al conclude that there is some evidence indicating that mindfulness meditation offers modest improvement in anxiety, depression and pain management, but little evidence supporting improved mental health overall. For example, there is insufficient evidence for positive mood, better sleeping, weight management or substance abuse. Under scientific scrutiny, meditation appears to confer some benefit, but no more than forms of psychotherapy or medication, and may not be more effective than various relaxation techniques. Despite fMRI (brain imaging) experiments that indicate definitive alterations to brain activity as a result of meditation (and persisting brain differences in seasoned meditators), the science has not (yet) identified an unequivocally strong correlation between meditation and overall, persistent well-being. Research continues; the caveat being that high-quality, rigorous research (long-term, randomized, double-blind, controlled testing) is not always the norm.
Does it work: The subjective (and philosophical) rationale
So what about the millions of meditators that claim significant benefit? Clearly there is something useful for them (beyond whatever placebo effect they derive from expecting to be calmer in their lives).
Let's look at each of the four types of meditation, without the scientific requirement of randomized, controlled testing.
1.Concentration: We humans are experts at over-reacting. Our emotional systems are tightly wound and ready to jump at the slightest provocation, from quotidian inconveniences to perceived criticisms, and the myriad injustices we suffer every day. Focusing on our breathing is one of the fastest and most effective ways to calm ourselves in moments of anxiety, frustration or anger.
2.Insight: We humans are blessed with a unique ability for metacognition - the ability to mentally step outside and evaluate our own trains of thought, testing our logic, our reasonableness and our understanding. We have the capacity to remove ourselves from the furor of the mental hurricanes that stir in our heads and view them for what they typically are - fabricated, unrealistic and destructive thought patterns. But this stepping back, or "going behind the waterfall to view the deluge," does not come naturally to us. It's a skill that most of us have no training in and very little practice with. Insight meditation addresses the gap by not only calming our minds with concentration, but generating insight into the nature and frequency of our perpetual over-reactions. As the Buddha taught, we have the opportunity to understand our suffering. And we can practice acceptance of how imperfect and unfair life can be.
3.Delight: Just as we are not naturally adept at self-soothing or evaluating our own thinking, nor are we instinctually inclined to stop and smell the roses. Yet there is so much incredible activity bundled into any given moment, which typically goes unnoticed. Pausing to attend to these sights and sounds is one of the most powerful ways to connect with our surroundings, and give significance to even the most banal situation. By attending to the constant fluctuation around us, this form of meditation allows us to serenely receive and appreciate the world through the majesty of the present moment.
4.Loving-kindness: Proponents insist that it brings powerful mental equanimity to the meditator: the deep empathy it invokes is the best antidote to feelings of jealousy, resentment and bitterness. It also helps to foster cooperation and mutual respect.
These four forms of meditation share a fundamental benefit that is virtually impossible for science to quantify: they each represent a different way of increasing personal freedom. They do this by inserting a pause - a mental space - between stimulus and response so that we are not captive to our first, automatic reactions. Meditation gives us more control by releasing us from the limitations of our instinctual, knee-jerk reactions: the self-awareness it generates within this pause empowers us to substitute a mindful response for a mindless reaction. At the same time, meditation breaks the inertia of our torturous mental churning, fueled as it often is by indignation. Our ability to manufacture the pause of deeper awareness that enhances our individual freedom differentiates us from other animals, who are hostage to their automatic responses.
The upshot
Does one have to meditate to enjoy the freedom of choosing more mindful responses? If by meditation we mean sitting still, with legs crossed and eyes closed, the answer is no. But broadly defined as attending to immediate experience, meditation is available to us anytime, without the formality of sitting. We can be driving, conversing, walking or running and be attentive to the present moment, especially our internal dialogues, inserting self-reflective pauses into the streams of our thoughts. Perhaps the "sit and be still" meditation is good practice for reinforcing the habit of self-reflection, but for those who are not convinced of the value of sitting meditation or find it impossible for more than a few minutes, each of the four categories of meditation are easily accessible no matter what we're doing. Meditation, as a form of intentional awareness, is at our constant disposal, helping to dampen our preliminary emotional reactions that so often conspire to make, as Milton's Satan described, "a hell of heaven."