Theta, Alpha, and the Brain on Hypnosis: What the EEG Shows

I studied cognitive science at Berkeley, and I spend a lot of time thinking about how the brain shifts gears. When you sit down to listen to a guided self-hypnosis session, your brain's electrical activity changes. You can measure these changes with an electroencephalogram, or EEG. EEG captures the combined electrical activity of neuronal assemblies, usually measured as specific frequencies representing slower and faster oscillations [1].

If you explore hypnotic suggestibility, you will quickly run into claims about theta and alpha brainwaves. People often say that hypnosis puts you in a specific theta state. The reality is more nuanced. EEG findings in hypnosis are inconsistent across studies, so treating any single-band claim as a settled fact is a mistake [1]. Let us look at what the research actually says about theta, alpha, and suggestibility.

The Brainwave Bands and Hypnosis

The human brain has a peculiar ability to transform endogenous mental representations into perceptual states [2]. The construction of perceptual states involves a top-down dynamic interplay between sensory processing, memory systems, attentional mechanisms, and higher-order cognitive functions [2]. This complex composition allows us to construct a coherent and meaningful perception of the external world based on our internal mental representations [2].

Such a top-down process is modulated by hypnosis, a social interaction in which the participant responds to verbal suggestions for imaginative experiences conveyed by the hypnotist [2]. These suggestions involve distortions in the environment awareness, such as conscious perception and memory, and sense of agency [2]. Hypnosis is a special rapport between the hypnotized person and the hypnotist in which the subject becomes deeply absorbed and focused on the hypnotist's voice with disconnection from extraneous stimuli [2].

According to Cardeña and Spiegel, hypnosis has three main components: absorption, dissociation, and hypnotic suggestibility [2]. The term absorption refers to the ability to become fully immersed in an experience [2]. Brain oscillations represent the combined electrical activity of neuronal assemblies [1]. Researchers measure these as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations [1].

Hypnosis has been most closely linked to power in the theta band and changes in gamma activity [1]. Theta oscillations are thought to play a critical role in the recording and recall of declarative memory and emotional limbic circuits [1]. Researchers propose that theta oscillations may facilitate some hypnotic responses [1]. Alpha is associated with relaxed, eyes-closed wakefulness [1]. Theta is associated with drowsiness and the edge of sleep, and in some studies with absorption [1]. EEG findings in hypnosis are inconsistent across studies, so never say "hypnosis puts you in theta" as fact [1].

A 2024 review examined research employing functional magnetic resonance imaging, positron emission tomography, and EEG methods to understand the cognitive neuroscience of hypnosis [2]. This review noted that EEG band oscillations serve as indicators of hypnotic states [2]. The reviewed functional connectivity findings support the notion that disruptions in the available integration between different components of the executive control network during hypnosis may correspond to altered subjective appraisals of the agency during the hypnotic response [2].

Suggestibility and Signal Variability

Hypnotic suggestibility is a fairly stable trait that varies a lot between people. Researchers measure it with standardized scales like the Stanford and Harvard scales. A 2020 study by Keshmiri et al. found that higher hypnotic suggestibility is associated with lower EEG signal variability in theta, alpha, and beta frequency bands [3]. This means that people who are highly suggestible tend to have more stable, less variable electrical patterns in these bands [3].

This finding suggests that the brains of highly suggestible individuals might operate with more rhythmic consistency in these bands [3]. However, it is worth noting that this was a specific sample and a single study [3]. Replication is needed to confirm these findings and see if they hold across different groups [3]. We must describe the evidence honestly and avoid overstating the results of one study [3]. The study provides a fascinating clue, but it is not a universal law [3].

Future studies investigating the effects of hypnosis on brain function should prioritize examining distinctive activation patterns across various neural networks [2]. This will help us understand how these patterns relate to hypnotizability [2]. A promising exploration avenue involves investigating how frontal lobes' neurochemical and aperiodic components of the EEG activity at waking-rest are linked to individual differences in hypnotizability [2].

Functional Connectivity Changes

When someone is actually hypnotized, the organization of their brain's electrical activity shifts. A 2014 study by Jamieson et al. found that hypnotic induction is followed by state-like changes in the organization of EEG functional connectivity in the theta and beta frequency bands in high-hypnotically susceptible individuals [4]. This means that the way different brain regions communicate during hypnosis changes, particularly in theta and beta bands, for people who are highly susceptible [4].

The findings support the notion that disruptions in the available integration between different components of the executive control network during hypnosis may correspond to altered subjective appraisals of the agency [2]. This aligns with dissociated and cold control theories of hypnosis [2]. Essentially, the brain networks that usually manage executive control reorganize, which might explain why hypnotic responses feel automatic [2].

According to Reyher, hypnosis research can be split into "intrinsic" and "instrumental" main approaches [2]. Intrinsic research attempts to understand the phenomena of hypnosis itself and to disclose the components of hypnotic responding [2]. In contrast, instrumental research uses hypnosis as a device to study a variety of psychological processes, including a dynamic interplay between sensory processing, memory systems, attentional mechanisms, and higher-order cognitive functions [2].

What This Means for Your Practice

If you use guided self-hypnosis or audio sessions, here is how to think about this research [1]. First, do not chase a specific frequency. There is no settled hypnosis frequency, and the EEG findings are inconsistent across studies [1]. Second, understand that suggestibility involves complex brain network integration [2].

Third, the downshift matters more than the frequency label. When your nervous system calms, your brain shifts toward alpha and theta, which is associated with relaxed, eyes-closed wakefulness and the edge of sleep [1]. Remember that EEG findings are inconsistent across studies. Treat any single-band claim with caution [1].

Theta is the most studied band in hypnosis research, but findings span alpha, beta, and gamma as well [2][1]. The goal of a hypnosis session is not to force your brain into a specific Hz range [1]. The goal is to create a state where your nervous system is downshifted and your attention is narrowed [1].

Putting It Into Practice

State precedes story. Automatic behavior is easiest to update when the nervous system is downshifted, attention is narrowed, and the brain has a vivid, specific alternative to rehearse. Willpower arguing with a stressed body is the slowest route. When you listen to a guided audio session, you are using sound to help guide your brain into a more receptive state [1].

You do not need to know your exact brainwave frequencies to benefit. You just need to find a quiet space, relax, and let the suggestions guide your attention. If your mind wanders, that is normal. Bringing your focus back to the voice is the practice.

Hypnosis is a state of deep absorption and focused attention [2]. By understanding the mechanisms behind hypnosis, you can approach your practice with more realistic expectations. You are not broken if you do not feel a specific theta wave. You are simply training your brain to downshift and focus.

Key takeaways

• Hypnosis has been most closely linked to power in the theta band and changes in gamma activity [1].
• Higher hypnotic suggestibility is associated with lower EEG signal variability in theta, alpha, and beta frequency bands [3].
• Hypnotic induction is followed by state-like changes in EEG functional connectivity in theta and beta bands in highly susceptible individuals [4].
• There is no settled hypnosis frequency, and EEG findings are inconsistent across studies [1].
• The goal is to downshift the nervous system and narrow attention, not to force a specific brainwave frequency [1].

Ready to experience a downshifted state for yourself? Try a guided self-hypnosis session designed to help you relax and focus. Explore Hypnothera Sessions

Sources & Further Reading

1. Jensen MP, Adachi T, Hakimian S (2015). Brain Oscillations, Hypnosis, and Hypnotizability. The American journal of clinical hypnosis. https://doi.org/10.1080/00029157.2014.976786
2. De Pascalis V (2024). Brain Functional Correlates of Resting Hypnosis and Hypnotizability: A Review. Brain sciences. https://doi.org/10.3390/brainsci14020115
3. Keshmiri S, Alimardani M, Shiomi M et al. (2020). Higher hypnotic suggestibility is associated with the lower EEG signal variability in theta, alpha, and beta frequency bands. PloS one. https://doi.org/10.1371/journal.pone.0230853
4. Jamieson GA, Burgess AP (2014). Hypnotic induction is followed by state-like changes in the organization of EEG functional connectivity in the theta and beta frequency bands in high-hypnotically susceptible individuals. Frontiers in human neuroscience. https://doi.org/10.3389/fnhum.2014.00528