The Science of Yoga

that spring day was gorgeous. An early shower had scrubbed the air, leaving it awash in sunlight. Flowers and trees were blooming. Men and women were shedding their coats. People fairly hummed along the sidewalks.
    We had just eaten lunch at Bertucci’s, a bustling restaurant where Khalsa had finished his meal with bomba —“the bomb” in Italian. The dessert consisted of balls of vanilla and chocolate gelato dipped in chocolate and covered with almonds, whipped cream, and chocolate sauce. I could see why his kids loved the place.
    Maybe it was the sugar high, or the beautiful day, or the yoga. Whatever the cause, the air fairly pulsed as Khalsa—a faculty member at the Harvard Medical School and one of the world’s leading authorities on the science of yoga—laid out his findings and ambitions. The friendly man of fifty-six turned out to have a lot.
    At Harvard, Khalsa had pursued a bold program of research that explored how yoga can soothe physically and emotionally. His focus was practical—and structured that way deliberately to demonstrate yoga’s social value. He had examined how its powers of unwinding can promote sleep and ease performance anxiety among musicians, and was now organizing a study to see if its calming influence could help high school students better fight theblues and everyday stress. Khalsa had ten yoga investigations in various stages of development.
    With energy and articulate zeal, he described his research as a way to help yoga break from its fringy past and go mainstream.
    “What ever happened to mental hygiene?” he asked rhetorically. “It doesn’t exist—and never did. When you went through high school, you were never taught how to deal with stress, how to deal with trauma, how to deal with tension and anxiety—with the whole list of mood impairments. There’s no preventive maintenance. We know how to prevent cavities. But we don’t teach children how to be resilient, how to cope with stress on a daily basis.
    “There’s a disconnect,” he continued. “We’ve done dental hygiene but not mental hygiene. So the question is, ‘How do we go from where we are now to where we need to be? ’ ”
    Khalsa argued that the only way to convince people about the value of yoga and establish a social consensus that encouraged wide practice was to conduct a thorough program of scientific research. He added that recommendations for regular toothbrushing had started that way and illustrated the potential value of good yoga studies.
    “That’s my mission in life,” Khalsa told me.
    This chapter examines not only Khalsa’s research but many inquiries into how yoga can lift moods and refresh the human spirit. It starts with the earliest research and ends with the most recent. The arc of the narrative is really a detective story. The studies began with the muscles (and how yoga can relax them), went on to study the blood (and how yoga breathing can reset its chemical balance), and eventually zeroed in on the subtleties of the nervous system (and how yoga poses can fine-tune its status). The discipline was found to lift and lower not only emotions but also their underlying constituents—the metabolism and the nervous system.
    The mood benefits detailed here are very real, unlike some of the aerobic claims of the last chapter. But the field also has its popular myths. They tend to be outright errors, probably rooted in ignorance rather than subtle shadings of the truth done with profit in mind.
    Psychologists tell us that a fundamental building block of emotional life is strong feeling, such as fury or affection. By definition, moods are considered less intense, more general, longer lasting, and less likely to arise from a particularstimulus. They are seen as drawn-out emotions. For instance, joy over a period of time produces a happy mood. Sadness over time results in depression. Unlike sharp feelings such as rage or surprise, moods tend to last for hours and days, if not weeks. If intense, they can color our life perceptions—at times dramatically.
    Moods are central to meaning in life and thus, in the judgment of psychologists, more important than money, status, and even personal relationships because they affect the happiness quotient that we assign to life activities. As the saying goes, a rich man in a bad mood can feel destitute, and a poor man in a good mood rich beyond words. To a surprising degree, moods define our being.
    It turns out that the word arose in the