How 'Yoga Nidra' Works

Why “yogic sleep” class is bringing veterans and CEOs to the mat

Go to one 30-minute yoga session—feel like you’ve slept for two hours. Hard to believe? I thought so too.

Yoga Nidra promises the equivalent of two hours of deep sleep in one 30-minute practice. I tried it at a yoga center in Golden Bay, New Zealand. For my first practice, I found myself staring at the ceiling of an earth yurt, feeling skeptical.

Yoga Nidra alleges regulation of hormones, stabilization of glucose levels, and alleviation of post traumatic stress disorder (PTSD). Sounds like big talk, especially for a practice that involves nothing but lying on your back for half an hour. But evidence is mounting in a big way. The benefits have been corroborated not just by Eastern medicine sympathizers, but by the U.S. Military and Silicon Valley.

Along with a group of ten others, Swami Karma Karuna, a certified Yoga Nidra instructor and director of the Anahata Yoga Center in Golden Bay, directed us to lie on our backs and cover up with a blanket. “Assure that you’re warm and comfortable, arms alongside your body. You’ll be in this position for the next 30 minutes,” she says. We rustled with our blankets and yoga mats until we were properly tucked in. “Let’s begin,” she says.

I came to Anahata for a three-week stay. I’d been living out of a backpack for 10 months, tramping across New Zealand. People like me who travel constantly are asked, “What are you running from?” (unmarried women are especially suspect: “No husband? No kids? You must be damaged goods.” But that’s an issue for a different article). Every day was a mini existential crisis: What is it all for?! I know I’m not the only millennial who got crushed by student debt and a jobless job market, and ended up with anxiety attacks. So when I found myself at a yoga center on a ridge overlooking the Tasman Sea, I thought: yes, maybe I am running from something, but this place will help.

Into the Deep

Described as “dynamic sleep,” the Yoga Nidra practice allows the body to deeply relax while the mind stays inwardly alert. Swami Satyananda Saraswati, who pioneered the practice in the early 1950s from ancient Tantric texts, calls it “reaching the border between waking and sleeping states.” Western medicine would call it the confluence of alpha and delta brainwaves.

Here’s what’s happening: Over the course of falling asleep, brain waves move from the active, thoughtful beta waves (14-40 Hz), then pass through the relaxed, thoughtless state of alpha waves (9-13 Hz), and enter the slowest frequency of deep sleep, delta waves (1-3 Hz). Yoga Nidra guides practitioners into the “hypnagogic state”—the threshold between alpha and theta waves—the knife’s edge where the body “sleeps” while the mind is lucid. Swami Karma Karuna describes it as a point “beyond the personality, where the logical, analytical aspect of the mind is suspended.” This passive/active state allows access to subconscious memory and repressed experiences—unlike hypnosis where the person is totally inert.

Moving systematically through the body, Karuna spoke rhythmically, “Right big toe, right little toe, top of the foot, heel of the foot, calf muscle…” Using what psychologists call “habituation,” the meditation works by using repeated stimuli to cause a diminishing response. By bringing your attention repeatedly to sensations in the body, you become habituated, and can then forget the sensation altogether (in the same way the strong initial smell of perfume gradually loses potency). This “forgetting” of the outside world allows you to draw attention inward. Karuna’s voice began to sound farther and farther away, “I’m going to guide you now through a series of visualizations.” The dark space behind my eyelids moved with inky, blotted shapes. The aim of visualizations, she says, is to shake out painful memories, conflicts, fears. She described it as “pulling out the weeds of the mind by the roots.”

A cognitive behavioral therapist would describe this as “brain plasticity,” or the ability to disengage old neural pathways and reinforce new, healthy ones. Yoga Nidra is essentially making space for the brain to rewire negative thought patterns and destructive habits. Karuna coos, “Imagine a red triangle...” The fingers of my left hand stiffened. “Now a steady blue flame...” My right foot twitched. My grip on the room loosened as I watched the visualizations flicker and dissolve.

“If we can remain in a relaxed state while accessing the unconscious areas of the mind,” Karuna says, “we can work with the deeper materials and correct physical and mental imbalances.” The potential for treatment ranges from anxiety and depression, to addiction and PTSD, she says. But could a red triangle really help my existential anxieties?

Science Weighs In

Researchers concede that the sample sizes are small and more longitudinal studies are needed, but the findings are hopeful. In two separate papers published in the Indian Journal of Physiology and Pharmacology researchers found Yoga Nidra improved blood pressure, heart rate variables, and hormone irregularities in women. Researchers at Shyam Shah Medical College measured fewer fluctuations in blood glucose levels in people with type-2 diabetes after 30 consecutive days of Yoga Nidra practice. All of this comes on the back of numerous studies firmly establishing measurable therapeutic effects of meditation, no matter the method, on everything from metabolic syndrome to clinical depression.

Yoga Nidra’s psychological benefits have opened a discussion with wide implications in the study of PTSD. Dr. Amanda Hull, a researcher at the U.S. Department of Veterans Affairs, is working to integrate Yoga Nidra, acupuncture, and qigong into the VA hospital structure. Alongside Dr. Hull, compelling research is happening at John F. Kennedy University involving Vietnam and Iraq war servicemen with severe PTSD. They reported “reduced rage, anxiety, and emotional reactivity” after eight weeks of regular Yoga Nidra practice. Similarly, at the Veterans Hospital in Long Beach, CA, researchers administered Yoga Nidra twice a week for 10 weeks to women who were victims of rape and military sexual trauma. Their 2014 study published in the International Journal of Yoga Therapy “showed significant decreases in negative thoughts of self-blame and depression.”

Consenting voices are ringing as far as Silicon Valley. CEO Charlie Kim, CEO of e-commerce company Next Jump, says investment in sleep “is a company problem.” Kim instituted Yoga Nidra company-wide, including offices in London and New York, offering it as “sleep class” every afternoon. Next Jump’s Head of Wellness, Peter Chica, says, “Companies invest in exercise and nutrition programs; it just makes sense to invest in sleep as well.” So, did it work? Sleep class was adopted immediately, Chica reported. “Everyone does it and even friends and family ask to come.” Next Jump employees reported better productivity, focus, and emotional balance. “The early adopters were the program’s best salespeople,” Chica says.

Purity and Popularity

With the rise in popularity, however, things have gotten murky. Spinoffs like “sleep class” and 72-hour weekend certifications make purists like Swami Karma Karuna uncomfortable. The Yoga Nidra teacher training she runs at the Anahata Yoga Retreat teaches methods developed by the Bihar School of Yoga in the 1960s, derived from the Tantric scriptures of fifth-century India. Karuna warns that the consequences of unearthing repressed experiences can be painful. “It’s important that you’re not guided into a subconscious place without the support of a knowledgeable teacher.”

In the fast-moving westernization of yoga, popularity can admittedly lead to dilution. Richard Miller, creator of iRest, a Yoga Nidra-inspired therapy, describes his version as “uniquely suitable for a Western audience”—noticeably stripped of references to sankalpa or shavasana. But Karuna is diplomatic: “Miller has developed one of the more authentic Yoga Nidra interpretations, and he has a good body of research that has helped from the scientific perspective.” Other offshoots include “Divine Sleep” class, developed Jennifer Reis of the Kripalu School of Yoga, and countless weekend certifications (like this one which takes only 24 hours).

Back in the yurt temple, Karuna’s voice was soft in my inner ear, “Slowly bring your awareness back into the body.” I heard her through the syrup of drowsiness, barely. I was feeling so warm, so peaceful, I resisted the instructions to follow. “Feel the sensation of the blanket against your skin, become aware of the cool air entering your nostrils.” I slowly wiggled my fingers and toes, shaking off the heaviness. We all sat up slowly, crossed-legged in a circle, smiling dreamily. “You have now concluded the practice of Yoga Nidra,” Karuna says. “Hari om tat sat.”

I can’t say if the 30-minute session was equal to two hours of REM for me. But I can say that afterward I felt undeniably refreshed, centered, and anxiety-free. So let me throw my own testimony into the ring, however anecdotal: Yoga Nidra might talk a big game, but it delivers. I arrived at Anahata feeling directionless and overwhelmed, and after three weeks of daily Yoga Nidra practice, I felt decidedly more purposeful and peaceful. Did the red triangle clear the neural pathways of my existential sufferings? Or did I just catch up on sleep? Either way, I left knowing I wasn’t running away anymore—I felt confident and courageous to face whatever was next.

The science community agrees further studies are needed to substantiate the health claims. But as Peter Chica of Next Jump pointed out, sometimes word of mouth can be more compelling than medical findings. In a market saturated with acai berries and wheatgrass, an honest “It worked for me, you should try it” is bringing everyone from war vets to computer programmers to the mat.

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