Close your eyes. Inhale. Exhale. Ahh. Can you feel your autonomic nervous system modulating itself?
It probably sounds like a weird question. But according to researchers like Harvard Medical School professor Sat Bir S. Khalsa, yoga and meditation practices might actually produce measurable changes in the activity of the autonomic nervous system--the bodily system that regulates, among other things, respiration, pulse rate, and digestion--as well as in brain activity and even gene expression. Researchers like Khalsa believe that these physiological effects, collectively dubbed the "relaxation response," lie at the root of yoga's touted health benefits, and that understanding the relaxation response may prove invaluable in the quest to develop new and improved treatments for sleep disturbances, anxiety disorders, and even some learning difficulties.
A yoga class. Via the Wikimedia Commons, Creative Commons Attribution-ShareAlike 2.0.
Of course, if you're a self-described Type A personality like me, it's easy to view this type of on-demand relaxation as little more than a yogic pipe dream. But curious about how the other half lives, on March 2nd, 2011, I decided to attend a presentation by Khalsa at the Harvard Graduate School of Education entitled Yoga: Practice and Research. I had seen advertisements for the talk plastered around the school, where I am currently studying educational neuroscience, and I was intrigued. Khalsa's evidence-based approach seemed like the perfect way for this high-strung science nerd to enter into the elusive world of yoga and meditation. The promise of attending an actual yoga class following Khalsa's lecture was an added perk. Would I bear witness as my fellow students soared to higher planes of consciousness? Would I finally experience, firsthand, relaxation in its purest form? Only time would tell.
Khalsa began his talk by briefly discussing yoga's history. My fellow attendees and I learned that artifactual evidence suggests that yoga originated in India as many as 5000 years ago. In its traditional form, yoga encompasses rhythmic breathing patterns, physical exercise--including the characteristic, sometimes pretzel-like poses known as "asanas"--and a range of mental activities which, according to Khalsa, lead to a state of "relaxed, focused attention." Although historically yoga has been practiced as a kind of mysticism, with the ultimate goal of reaching a state of "enlightment," in recent years increasing attention has been paid by researchers and the media to yoga's therapeutic potential, both medical and psychological. This positive attention may help to explain yoga's meteoric rise to popularity far beyond the Indian subcontinent. As of 2008, nearly 16 million Americans actively participated in yoga, with a majority of novice practitioners citing wellness or "stress management" as their main motivation for taking up the practice.
As a dyed-in-the-wool data-lover, I found these statistics compelling, but not convincing. Popularity aside, I wondered about the scientific evidence supporting yoga's espoused health benefits. I thus listened with eager ears as Khalsa proceeded to discuss some research findings related to yoga's effects on the body. Surprisingly, I quickly discovered that yoga research is nothing new. A number of landmark studies dating back to the 1930s have looked at the effects of yoga and, relatedly, meditation, on everything from heart rates to brain waves.
While some of these studies yielded conflicting results--it appears that even expert yogis cannot, alas, temporarily stop their own hearts from beating--others provide strong evidence for the existence of the relaxation response. As early as the 1950s, scientists had discovered that yoga and meditation reliably produce a cascade of physiological effects, including decreased oxygen consumption, slowed breathing, increased blood flow to the limbs, and changes in patterns of brain activity associated with attention. Described in a 1971 article as reflecting a "wakeful hypometabolic physiologic state," these effects appear to account for the feelings of subjective calmness and well being reported by yoga and meditation practitioners.