Here’s what you’ll learn when you read this story:

• Researchers believe that chanting may induce altered states of consciousness—but they aren’t completely sure why.
• Possible reasons includes vagus nerve stimulation, increased interpersonal synchrony, and tapping into deeply rooted spiritual beliefs.
• The altered states people experience as a result of chanting vary, ranging from profound hallucinations to feeling more connected with those around you.

In a 14th-century temple in Thailand, Buddhist children in orange robes fidget on their cushions, as monks chant all around them. In forests in Canada, First Nations people perform a ceremony around a fire, also chanting. In Catholic masses under vaulted ceilings, believers intone the Apostles’ Creed as a Gregorian chant. And in Tanzania, Maasai use rhythmic chants in ceremonies like Adumu—the jumping dance.

Chanting is a universal human behavior, yet one that is hardly studied.

Gemma Perry, PhD, is a psychologist and one of a handful of researchers who specialize in chanting and its impacts on consciousness. She has investigated how the practice is used around the world. For example, shamans chant to enter altered states believed to be vital for healing and modifying behavior. Indigenous Australians use it to connect with the Ancestral world. Sufis use chanting, dance, and breathing to connect to God and enter into states of trance. And Yogic traditions believe that chanting practices are a way of reaching states of consciousness beyond the disturbances of the mind.

These experiences “often involve overwhelming positive emotions, distortion of time and space, and a loss of boundaries between oneself, others and nature,” Perry wrote in one study. Like with psychedelics, those who achieve altered states through chanting often say the experience is one of the most meaningful of their lives and makes them feel more “at one” with those around them. Chanting is also reported to lift depression. But scientists are only beginning to understand why chanting is seen as the portal for these experiences.

While researchers aren’t exactly sure why chanting induces these mystical experiences, they point to a few possibilities.

1. Chanting—even silent chanting—requires that the person focus intently on something besides themselves, which helps ease rumination.
2. If you’re chanting certain sounds aloud, you stimulate the vagus nerve, and that has been demonstrated to reduce depression.
3. If you’re chanting with others, your attention is even more absorbed in the effort to synchronize with those around you, and that synchrony promotes connection.
4. If you’re chanting a song or sound synchronously with others that’s rooted in a shared spiritual belief, that could impact a lot of systems in your brain and body.

In terms of altered states of consciousness, Perry says, there’s the “dissolution of ego” which causes the person to feel like they’re merging with nature or the people around them; and there’s “flow” which causes the person to be connected with the activity. She says chanting works on the default mode network (DFN), the same system that’s affected by psychedelics. The DFN is a group of areas in the brain (there’s no clear agreement on what’s included) that has to do with self-referential thinking—like ruminating or worrying. So practices that cause the DFN to operate differently can help relieve people of their anxiety or negative narratives.

While silent meditation requires intense external focus, group chanting takes that up several notches. You’re now not only focused on your own practice but on staying in sync with those around you in your coordinated vocalization, breath control, and interpersonal synchrony. That appears to not only get you out of your own rumination but strengthens social connections.

Altering one’s state through synchrony is the goal of Taketina, a chanting practice developed in the 1970s by composer Reinhard Flescher. Taketina includes coordinated dance, clapping, and chanting without a specific spiritual motivation.

Participants must pay intense attention to the rhythm and the people around them. This kind of intense attention—which can also be seen in Sufi dancing—stimulates the endocannabinoid system. This system regulates and controls many of our most critical bodily functions, such as learning and memory, emotional processing, sleep, temperature control, pain control, inflammatory and immune responses, and eating. It is the system affected by marijuana. A neurotransmitter in the system, called anandamide, is known as the “bliss molecule.” It causes the feelings of happiness and well-being when triggered by marijuana, but also by group chanting.

“You can get [to an altered state] mechanically through these cognitively demanding tasks,” Perry says. If a ritual requires that you say a complex chant, breathe in a certain way, place things in a fire in a specific order or pour oil over an icon at a specific moment, you’re likely to be so absorbed in making sure you do the ritual correctly you won’t have brain space to think about your depression-inducing thoughts. “It’s quite cognitively demanding and it keeps us completely focused on the practice,” she says.

Because group chanting requires you to synchronize with those around you, it also increases social connection by training the brain to resonate with the oscillations around it, Perry says. It lets your internal rhythms fall into harmony with those outside of it.

Rhythmic synchrony could happen with any kind of chanting. But a different group of researchers wanted to know whether the effects of chanting are really that agnostic. The group, from the Department of Psychiatry, Advanced Center for Yoga, National Institute of Mental Health and Neurosciences, Bangalore, tested the impacts of practitioners chanting “om”—a sound that represents the divine in Hinduism—or chanting a different sound. They used functional magnetic resonance imaging (fMRI) to measure brain activity through changes in blood flow. The fMRI highlights active brain regions by tracking oxygen usage, which helps doctors and researchers map brain function.

In this case, the study included only nine male subjects, four of whom were regular om chanters and the others were not. All the subjects were trained to chant om without distress or interruption—chanting the O syllable for 5 seconds and the M for 10. The control condition—the other activity—was to make the “ssssss” sound for 15 seconds.

Both involved breathing focus. But, according to the study, making the long M sound stimulates the vagus nerve through branches around the ears. The vagus nerve is the longest nerve of the autonomic nervous system—it connects the brain to the heart, lungs, and digestive system. Stimulating the vagus nerve reduces anxiety by lowering heart rate and blood pressure.

What the researchers found was that those chanting oms had significant deactivation of parts of the brain such as the amygdala, anterior cingulate gyrus, hippocampus, insula, orbitofrontal cortex, parahippocampal gyrus, and thalamus. These structures are key components of the limbic system, which regulate emotions, behavior, motivation, and memory. Subjects didn’t have that deactivation when chanting “sssss.”

Other researchers examined the question of whether the meaning of the mantra was key in impacting chanters. Junling Gao, PhD, is another researcher who has done significant studies on chanting. His team took 21 Buddhist chanters and measured their emotional impacts with an electroencephalography (EEG) while they looked at neutral or upsetting images.

These subjects didn’t chant out loud—so that long M wasn’t resonating around the ears. Instead, they chanted silently. The researchers tested them when they weren’t chanting at all, chanting the name of the Buddha (Amitābha), or chanting Santa Claus.

Then the researchers showed them emotionally upsetting images, such as photos of aimed guns or mutilation. The silent non-chanters and those chanting Santa Claus showed increased emotional reactivity when they saw the images. In other words, they became stressed. On the other hand, those chanting Amitābha did not.

One thing Perry is studying is whether the response people have to chanting is inherent in the chanters themselves. Perry took up chanting because she suffered from depression and found that chanting gave her relief. She has also reached mystical states while chanting. She is someone who measures a high level of “absorption,” which means that she is more likely to be brought to tears by a beautiful piece of music or be breathless with awe at gorgeous landscapes than people who are low in absorption.

In her research, she found that the chanters who reached mystical states were likely to self-identify as measuring high on absorption. And it didn’t matter what form of chanting they were practicing.

“Among the regular chanters, 60 percent were reporting to have these profound alterations in consciousness, no matter what tradition they were from,” Perry says.

“Some people have really profound experiences, you know, visions and all these sorts of things,” she says. “I’m more interested in how that actually impacts them in the world. So if you have an altered state, in which you feel connected to everything, then maybe you come out of that experience a little bit kinder, like, ‘Hey, I’m connected to that person,’ and you just navigate the world a little bit differently.”