The Neuroscience of Shamanic Trance

A 2021 study published in Frontiers in Human Neuroscience explored what happens in the brain when shamanic practitioners enter a trance state during drumming. The results show that shamanic trance is a distinct non-drug-induced altered state of consciousness with measurable brain changes and subjective experiences that can, in some ways, resemble psychedelic experiences. 

Using high-density electroencephalography (EEG), a brain-scanning technique that records electrical activity through small sensors on the scalp, researchers compared two groups: 24 experienced shamanic practitioners and 24 control participants with no background in trance or shamanic practice. Everyone completed three conditions: quiet rest, listening to rhythmic shamanic drumming and listening to classical music.

Participants also filled out a standardized survey of altered consciousness called the OAV scale, which measures experiences such as visual imagery, feelings of unity, insight, and emotional intensity.

During shamanic drumming, the practitioners reported significantly stronger altered-state experiences than controls in eight of the 11 OAV domains, indicating that drumming reliably induced a profound shift in consciousness for trained practitioners. During classical music, however, there were no differences between the two groups; this shows that the effect was specific to the drumming condition.

To put their results in context, the researchers compared the practitioners’ OAV scores with previously published data from over 500 psychedelic drug users who had taken psilocybin, ketamine, or 3,4-methylenedioxymethamphetamine, commonly known as "Molly" or "Ecstacy". The shamanic practitioners’ reports were as high or higher than those of psychedelic users in several key domains and similar in others, suggesting that the subjective intensity of shamanic trance can match that of psychedelic experiences without taking any substance.

EEG recordings provided further insights, wherein the researchers measured different brainwave frequencies. The human brain vibrates at different frequencies, each linked to a mental state:

• Delta (0.5–4 Hz): deep sleep
• Theta (4–8 Hz): trance, dreaming and deep meditation
• Alpha (8–12 Hz): calm wakefulness, relaxation
• Beta (14–30 Hz): alertness, focus and problem-solving
• Gamma (30 Hz and above): insight, integration and peak awareness

During trance, EEG recordings of practitioners showed increased gamma power, which correlated with vivid inner imagery and visionary experiences. They also showed decreased low alpha (8–10 Hz) and increased low beta (14–18 Hz) connectivity, reflecting a shift from relaxed to more actively engaged mental processing.

The study also found reduced gamma-band signal diversity, meaning the brain’s activity became more synchronized, which is often associated with deep insight or feelings of unity.

While the subjective experiences of shamanic trance may overlap with those of psychedelics, the neural signatures were distinct. The authors conclude that the shamanic state of consciousness represents a unique, self-generated brain state—not a mimicry of the psychedelic state, but a different route to an equally rich form of altered awareness.