On the night of the recent winter solstice, a group of two-dozen adults paid $25 each to take a nap in a yoga studio.

At least, that's how it appears from the outside. Ask Nicole Alcyon, who's leading this sound-healing session at Awakenings Wellness Center in Southeast Portland, and she'll explain there's something much deeper going on.

Still, what it looks like is a hippie slumber party.

The mostly middle-aged attendees are sprawled on the floor, some prone, others propped up on back rests. Most are wrapped in blankets. For the next 90 minutes, Alcyon—a wispy brunette with the gentle disposition of a kindergarten teacher—performs what is essentially an intimate ambient music concert.

Alcyon begins by pacing the room. While her partner, Tom, thumps a small hand drum, she lightly bashes a small gong in each person's face, letting the vibrations run across their bodies. Next are the tuning forks, which sound like a blissful drop of tinnitus being placed straight in your ear. She follows by playing a larger gong, sending out low, shimmering reverberations that almost seem to ring with feedback. And then, the singing bowls. Kneeling among 13 frosted-glass bowls of varying sizes, she taps the rims in a pattern that appears improvised but eventually forms a chiming, identifiable melody.

By the time she finishes, a chorus of heavy breathing and full-on snoring cuts through the stillness of the room.

It's precisely the response Alcyon is hoping for. In her pre-session spiel, she says the goal for the evening is to leave the assembled group feeling like bears awakening from hibernation. She also says some other things that, for the less spiritually enlightened, probably sound a bit out-there—stuff about "hypno-chakra therapy" and the "Solfeggio scale" and the significance of the 3-6-9 pattern. At its core, though, the concept of sound healing is simple enough for even a granola-phobe to grasp.

"To get very basic, in layman terms, the frequencies just promote a deep sense of relaxation," says Alcyon, who describes herself as "a certified hypnotherapist, intuitive sound healer, and angel therapy practitioner."

"When we can relax, and our bodies can rest, it allows for healing. Sleep can be very healing. As we are in this state of deep relaxation, it allows for us to enter into this greater healing state, where our body has that ability and that space to do its own natural healing and balancing."

When she moved to Portland from Los Angeles a decade ago, Alcyon was, as far as she knew, the only practitioner of sound healing in town. In the past few years, she says, the practice has steadily grown in popularity. A quick Google search shows you almost can't run a wellness center or acupuncture clinic without offering some form of sound healing.

Alcyon runs her own practice, Triniti Healing, out of Awakenings, and holds these "meet-ups" about every two weeks. It always draws a crowd. In an increasingly stressful world, sound healing is on the verge of joining yoga and meditation in mainstream consciousness.

It's not just about achieving a deeper state of sleep, either. As Alcyon explains it, it has to do with accessing the brain waves associated with relaxation through soothing tones and rhythms, and using specific frequencies that are thought to "clear out" dissonant or discordant energy. In effect, it's much like meditation, except instead of regulated breathing, the path to betterment is guided by sound.

"In meditation, there's usually some guidance to focus on your breath or focus on your own thoughts, and this just allows people to go deeper," she says. "They have something outside of them, and that something outside of them is deeply relaxing. It naturally takes them into a deep meditative state they wouldn't naturally go in if they were just closing their eyes and taking deep breaths."

At the solstice meet-up, a silver-haired suburban dad named David—who's quick to point out he's "not as crunchy" as some of the other people in attendance—puts it another way. When a certain frequency hits a chakra—one of the seven points of energy that Buddhists believe run through the human body—he swears he can feel if it's out of balance. As the session goes on, he can also feel the realignment happening. He says it's not unlike seeing a chiropractor, only for the spirit rather than the physical body.

Alcyon agrees with the comparison.

"It's bringing your energetic field into alignment," she says. "It's harmonizing the body with the mind, with the spirit. In that way, it can be very much like a chiropractic session. It brings the balance of harmony into alignment, and that's ultimately what people receive from these sessions."

Alcyon mostly attributes the growing acceptance of sound healing to media exposure (Dr. Oz has done segments on it) and the general way information spreads in the digital age. But she also agrees that, at a time of widespread anxiety, any form of relief starts to look appealing.

"More and more people are waking up to, 'What is this world all about?' And I think, because of all the stress, we begin questioning, 'Am I living meaningfully?'" she says. "And I think as people seek out meaning in life, and what's going to fulfill them, this somehow gets into their sphere of reality. Because it is a deeper way to meditate, and it's a way to achieve greater balance and clarity within really easily."