OVER THE PAST five years, I’ve had countless interactions with Sarasvati Hewitt. Each one of them has been life-changing. That’s not hyperbole. On the contrary, it’s an empirically predictable and increasingly medically accepted outcome of Hewitt’s work.

A yoga practitioner based in Portland, Oregon, with over two decades of experience, Hewitt has spent the past five years focusing exclusively on yin yoga — a slow-paced practice in which poses are held for up to five minutes. The benefits of this increasingly popular style are purported to be many, among them: its longer holds increase circulation and improve flexibility. Additionally, its meditative nature promotes emotional processing, which Hewitt likens to cognitive behavioral therapy, and which has been documented to reduce the stress, anxiety, and insomnia linked to both modern life and clinically diagnosed PTSD.

“On the mat, it’s kind of boring,” Hewitt explains. “That’s honestly one of the most important things about yin: The process that naturally happens when we are sitting and left to our own thoughts is profound. As always, yoga is like, ‘Yeah, we told you that 5,000 years ago. That’s why we were just sitting, closing our eyes. Do nothing, and everything is there.’”

Hewitt’s sardonic declaration highlights her refreshing candor in a sea of saccharine yogic platitudes. It also reveals her current mission: to illuminate the hard science behind yin yoga’s holistic healing benefits. “One of the things I jokingly say to my students is, ‘Kaiser Permanente doesn't care about my chakras,’” she laughs. “That’s my way of being like, you gotta bring them data — that’s how we’re able to bill insurance. But the reality is: Our understanding of yin’s benefits first came from the experience. It was the experience that led people to actually do more research.”

This includes Hewitt’s own experience. She did yin for 750 days in a row to test its veracity, with her personal results corroborated by her classes. “My classes were getting crazy big,” she recalls. “Students were saying: ‘This is helping my body. This is helping me sleep. This is helping my mood.’ How does it work? Psychologists and therapists were coming to me asking, ‘What are you doing?’ I was like, ‘I don’t know. I gotta go figure out how this is working so that we can explain it and attempt to replicate it in some form, with consistency.’”

The mission led her to study the neuroscience of yoga and trauma at the Kripalu Center for Yoga & Health under psychologist Dr. Jim Hopper, as well as interpersonal neurobiology at Portland State University. Hewitt also trained under Matthew Schulman, a pupil of Paul Grilley, who is widely credited for introducing yin to the United States. A nonlinear combination of these interactions and her own teaching experience propelled Hewitt toward Dr. Lisa Sardinia’s studies on the relationship between the gut and anxiety; Dr. Matthew Walker’s examinations of sleep and its impact on human health; and the documentary “Stress: Portrait of a Killer,” with Stanford University neurobiologist Robert Sapolsky. Collectively, this education led Hewitt to form a foundational belief in what she calls “the triangle connection between mental health, the gut, and sleep.” Put simply: Studies show that anxiety (mental health) is directly related to the gut, and gut health is directly related to sleep. If we don’t sleep for even one night, we destroy more than a third of our gut bacteria. This destabilizes the digestive system, making us prone to anxiety, and making it harder to sleep.

“When we lay down at night,” Hewitt elaborates, “we get insomnia because the brain starts the kind of processing that it should have done throughout the day. If you process on the mat, it removes insomnia, so you sleep better and you dream better. You wake up not only less stressed but also physically better because another thing that happens only when you dream is that all the muscles relax, so yin is like the first domino that sets off a huge domino effect of health.”

This exponential outcome, Hewitt believes, can be triggered by as little as five foundational poses held for three to five minutes each: Dragonfly, a forward fold from a seated position with the legs wide; Sphinx, a backbend achieved from lying on your front, placing your elbows directly underneath your shoulder blades and gently pushing up; Full or Half Saddle, a full-body stretch accomplished by sitting on or between your feet and leaning backward; Swan, the yin variation of Pigeon pose, in which you lie with one leg bent in front of you and one stretched backward, lying over your front knee; and a classic twist, wherein you recline on your back, squeeze your knees together and drop them to one side while looking the opposite way.

It’s that simple. “You can literally be wearing sweatpants under a blanket, crying in the dark and you get an A-plus,” Hewitt confirms. “You just need a little bit of room and a way to time it. That’s about it.”

If you can’t make it to Hewitt’s in-person class at the Yin Yoga Space in Portland, this video walks you through an abbreviated practice. She also offers destination retreats and private sessions, as detailed on her website.