How Hypnosis Works

For something that has been practised for well over a century, hypnosis is surprisingly misunderstood. Part of the problem is that the theatrical version — stage performers making people do silly things — has dominated public perception. But in research laboratories and clinical settings, the picture is far more nuanced and genuinely fascinating.

What Is Hypnosis, Neurologically?

Modern brain imaging technology, particularly functional MRI (fMRI), has given us remarkable insights into what happens during hypnosis. Research from Stanford University, published in the journal Cerebral Cortex, identified three distinct changes in brain activity during hypnosis:

1. Reduced Activity in the Dorsal Anterior Cingulate

This brain region is part of what's called the "salience network" — it helps you evaluate what's important and what to pay attention to. During hypnosis, activity here decreases, which means you become less self-conscious, less worried about what's happening, and more absorbed in the therapeutic experience.

2. Increased Connectivity Between Two Key Areas

The dorsolateral prefrontal cortex (involved in planning and decision-making) shows increased communication with the insula (which helps process body sensations and emotions). In practical terms, this means the mind and body become more connected during hypnosis — which is precisely why hypnosis can influence physical responses like pain perception, heart rate and muscle tension.

3. Reduced Connectivity in Self-Monitoring

There's decreased communication between the dorsolateral prefrontal cortex and the default mode network (the brain's "autopilot" that governs self-reflection). This explains why people under hypnosis are less likely to second-guess or critically evaluate suggestions — they simply engage with them more directly.

The Conscious and Subconscious Mind

While neuroscientists tend to avoid the terms "conscious" and "subconscious" (they're simplifications of a much more complex reality), they remain useful for understanding how hypnotherapy works in practice.

Your conscious mind handles deliberate thought, analysis and decision-making. It's the part that's reading this page right now. Your subconscious handles everything else — automatic behaviours, emotional responses, habits, memories, bodily functions. It processes vastly more information than your conscious mind and operates much faster.

Many of the problems people bring to hypnotherapy are maintained at a subconscious level. Anxiety persists despite knowing rationally that the situation isn't dangerous. Phobias persist despite understanding they're irrational. Overeating happens despite knowing the consequences. The conscious mind wants to change, but the subconscious resists.

Hypnosis provides a way to communicate with the subconscious mind more directly, bypassing the usual analytical filtering that prevents new information from taking root.

Suggestibility and Neuroplasticity

The brain is not fixed. Neuroplasticity — the brain's ability to form new neural pathways and reorganise existing ones — continues throughout life. Every time you learn something new, practise a skill, or form a habit, your brain physically changes.

Hypnosis appears to enhance neuroplasticity in the moment, making the brain more receptive to forming new patterns. When a hypnotherapist suggests, for example, that a client will feel calm in situations that previously triggered anxiety, they're essentially guiding the brain to create new neural pathways for responding to those situations. With repetition (through sessions and self-hypnosis practice), these pathways strengthen until the new response becomes automatic.

The Role of Relaxation

Deep relaxation is a significant component of most hypnotic inductions, though it's worth noting that relaxation itself is not hypnosis. You can be deeply relaxed without being in a hypnotic state, and some hypnotic techniques don't involve relaxation at all (alert hypnosis, for instance).

However, relaxation serves several important therapeutic functions. It reduces cortisol (the stress hormone), activates the parasympathetic nervous system (the "rest and digest" response), reduces muscle tension, and creates a mental state more conducive to accepting therapeutic suggestions. For conditions like insomnia and anxiety, the relaxation itself is directly therapeutic.

What Research Tells Us

The evidence for hypnotherapy continues to grow. Some key findings:

• A meta-analysis in Neuroscience & Biobehavioral Reviews confirmed that hypnosis produces genuine neurophysiological effects distinct from placebo
• Research in the International Journal of Clinical and Experimental Hypnosis demonstrated significant pain reduction through hypnosis, supported by brain imaging evidence
• Studies published in Sleep Medicine Reviews showed hypnotic suggestions specifically targeting deep sleep increased slow-wave sleep duration
• The NHS lists hypnotherapy as a recognised complementary therapy

Individual Differences in Hypnotic Responsiveness

Not everyone responds to hypnosis in the same way. Research suggests that about 10-15% of people are highly hypnotisable, 10-15% find it difficult, and the remaining 70-80% fall somewhere in between.

Importantly, lower natural hypnotisability does not mean hypnotherapy can't help you. Hypnotic responsiveness can be enhanced with practice, and many therapeutic techniques work perfectly well with moderate levels of trance. What matters most is your motivation and willingness to engage with the process.

Why Understanding the Science Matters

For some people, understanding the neurological basis of hypnosis removes the uncertainty and makes them more comfortable trying it. It's not mystical. It's not magic. It's a well-documented alteration in brain function that creates conditions for therapeutic change. The same brain mechanisms that maintain unhelpful patterns can be harnessed to create healthier ones.

If you'd like to understand more about how this translates into practice, read about what clinical hypnotherapy involves or what to expect in your first session.