From the Guidelines
The most consistent change in brain activity associated with hypnosis is theta activity. Theta waves, which oscillate at approximately 4-8 Hz, typically increase during hypnotic states 1. This increase in theta activity reflects the altered state of consciousness that characterizes hypnosis, where individuals often experience deep relaxation while maintaining focused attention. During hypnosis, the brain shifts from normal waking consciousness (dominated by beta waves) to a more receptive state where theta waves become more prominent.
Key Points
- The enhanced theta activity likely contributes to the hypnotic phenomena of absorption, dissociation, and heightened responsiveness to suggestion that are hallmarks of the hypnotic experience.
- While other brainwave patterns may change during hypnosis, the increase in theta activity represents the most consistent and characteristic neurophysiological signature of the hypnotic state.
- The provided evidence on hypnotherapy for irritable bowel syndrome (IBS) and its effects on the gut-brain axis does not directly address the changes in brain activity associated with hypnosis 1.
- However, the study on hypnosis in cancer care suggests that hypnosis can have a positive impact on various symptoms, including pain, fatigue, and anxiety, which may be related to the changes in brain activity during hypnosis 1.
From the Research
Brain Activity Associated with Hypnosis
The most consistent change in brain activity associated with hypnosis is related to specific frequency bands. The key findings are:
- Theta activity is often linked to hypnosis, with studies suggesting that it may be an index of relaxation that continues after hypnosis 2, and that theta oscillations may facilitate hypnotic responses 3.
- Alpha activity is also associated with hypnosis, particularly in high hypnotically susceptible individuals, where it may index the hypnotic experience and susceptibility 2.
- Beta activity has been less consistently linked to hypnosis, although one study found that higher hypnotic suggestibility is associated with lower variability in beta frequency bands 4.
- 40 Hz activity (gamma oscillations) has been linked to hypnosis, with changes in gamma activity observed during hypnosis potentially underlying some hypnotic responses 3.
Key Findings
Some of the key findings from the studies include:
- Higher hypnotic suggestibility is associated with lower variability in theta, alpha, and beta frequency bands 4.
- Theta activity is positively associated with response to hypnosis, with EEG oscillations of θ activity showing greater amplitudes for highly hypnotizable subjects over the left hemisphere 5.
- Alpha activity is associated with hypnotic susceptibility, with high susceptibles having greater alpha power than lows during both prehypnosis and hypnosis conditions 2.
- Changes in brain activity during hypnosis include reduced activity in the default mode network, increased functional connectivity between the executive control network and the salience network, and reduced connectivity between the executive control network and the default mode network 6.