What is EMDR? The Science Behind the Therapy
Over the past few years, EMDR has moved from being something only clinicians had heard of to a term that appears regularly in conversations about mental health, in magazine features, and in the accounts of public figures who have spoken openly about their experience of it. The curiosity this has generated is well-placed. EMDR is a genuinely interesting therapy, not just in what it does but in why it works and in the questions it raises about how the brain stores and processes difficult experiences.
But for many people, the description they’ve encountered is liited; something about eye movements, something about trauma. Which leaves a lot unexplained. What is actually happening during an EMDR session? Why would moving your eyes back and forth help with something as serious as PTSD? Is it just for trauma, or can it help with other things? And is there real science behind it, or is it more speculative than it sounds?
The answers are more substantive, and more interesting, than the surface-level description tends to suggest.
Where EMDR came from
EMDR (Eye Movement Desensitisation and Reprocessing) was developed by American psychologist Francine Shapiro in the late 1980s. The original story is often cited; Shapiro noticed, apparently by chance, that making rapid lateral eye movements while thinking about distressing material seemed to reduce its emotional intensity. She developed this observation into a structured therapeutic protocol, tested it, and published her initial findings in 1989.
What followed was several decades of research, refinement, and (initially) significant scepticism. Eye movements as a therapeutic tool stuck many clinicians as implausible. The mechanism wasn’t clear. The name sounded more like a description of a technique than a coherent psychological treatment.
The scepticism has largely given way to a substantial evidence base. EMDR now holds the highest level of recommendation for treating PTSD from NICE in the UK, the World Health Organisation, the American Psychological Association, and the International Society for Traumatic Stress Studies. More than 10,000 therapists in the UK alone are trained in it. The question of whether it works has been largely settled. The more interesting question - why it works - is still being actively researched.
How the brain stores traumatic memories differently
To understand what EMDR is doing, it helps to understand what trauma does to memory in the first place.
Most memories are processed and stored in a way that allows them to be integrated into the broader context of your life. You can remember something difficult, access the emotions it carries, and over time the memory becomes something that belongs in the past. The emotional charge associated with it diminishes. It becomes, the in the most functional sense, a memory rather than a lived experience.
Traumatic memories don’t always follow this path. The theoretical framework underlying EMDR (Francine Shapiro’s Adaptive Information Processing model) proposes that highly distressing events can disrupt the brain’s normal memory processing mechanism, leaving the memory stored in a kind of unprocessed state; fragmented, emotionally raw, and without the contextual information that would situate it firmly in the past. When triggered, it doesn’t feel like remembering something that happened. It feels like it is happening; in the body, in the nervous system, in the emotional response.
This connects to a broader understanding of how trauma affects the body and brain. (explored in more depth in our article on intergenerational trauma and emotional patterns, and in Bessel can Der Kolk’s influential - but recently contested - research on why trauma is experienced physically rather than purely cognitively).
Traumatic memory doesn’t feel like remembering something that happened. It feels like it is happening. EMDR works, in part, by giving the brain the conditions it needs to finally move that memory into the past.
What actually happens in an EMDR session
EMDR follows a structured eight-phase protocol. The early phases involve building a thorough history with the therapist, identifying specific memories or experiences to work on, and developing the internal resources (the capacity to stay gorunded and regulated) that will make the processing phases safe to enter.
The core processing phase involves the client holding a specific traumatic memory in mind, including the image, the associated negative belief about themselves, and the physical sensation it produces in the body, while simultaneously engaging in bilateral stimulation. In most sessions, this means visually tracking the therapist’s hand as it moves back and forth in from of the face, producing a series of rapid lateral eye movements. Bilateral stimulation can also be delivered through alternating taps on the hands or knees, or through auditory tones delivered alternatively to each ear.
After each set of eye movements, the client is invited to notice whatever has arisen; an image, a thought, an sensation, an emotion, and the process continues, following where the memory leads until its emotional intensity has reduced significantly and the associated belief has shifted. The session closes with a careful stabilisation phase to ensure the client leaves in a regulated state.
What many people notice, and find difficult to explain, is how different this feels from talking therapy. There is considerably less verbal processing of the content of the memory. The therapist doesn’t analyse or interpret. The work is more internal, following a process that the client’s own brain appears to be conducting, with the bilateral stimulation as the facilitating condition rather than the active ingredient.
Why it works: the science behind the eye movements
Here is where the genuine scientific debate is, and it is worth engaging with honestly, because the eye movements are both the most recognisable feature of EMDR and, potentially, not the most important one.
The leading current therapy is the working memory taxation hypothesis, developed by researchers including Martin Va den Hout and Iris Engelhard. Working memory is the brains’ short-term processing space; the mental workspace in which you hold and manipulate information in real time. It has a limited capacity. The hypothesis proposes that holding a distressing memory in mind while simultaneously tracking a moving object taxes this capacity in a specific way; the working memory system becomes partially occupied by the tracking task, reducing resources available to the emotional processing of the memory. The result is that. the memory becomes less vivid, and less emotionally intense, with each set of eye movements.
Studies by Van den Hout, Engelhard and colleagues have found that taxing working memory through various dual tasks, not just eye movements, but also tasks like mental arithmetic or Tetris, reduces the vividness and emotional intensity of distressing memories in measurable ways. This suggests that bilateral eye movements may not be uniquely necessary; what matters is the dual attention task, not the specific modality.
A 2025 study published in Frontiers in Psychiatry found that an alternative attentional task produced equivalent reductions in distress to conventional EMDR, suggesting the active mechanism may be more fundamentally about engaging attention control networks than about the specific movements involved. Neuro-imaging research supports this: successful EMDR therapy is associated with enhanced activation in prefrontal regions responsible for attention control and emotional regulation; the same regions that are typically underactive in people with PTSD.
The eye movements may be how EMDR was discovered. They may not be the reason it works. What the research increasingly points toward is the dual attention task — the act of holding something difficult in mind while simultaneously being anchored in the present.
This has implications beyond trauma processing. It suggests that EMDR is working at the level of memory consolidation and attention regulation; processes that are relevant not only to PTSD but to the wider range of conditions in which distressing memories play a maintaining role.
What EMDR can and can’t help with
EMDR's strongest evidence base is for PTSD and complex PTSD, where it is recommended as a first-line treatment alongside trauma-focused CBT. A 2025 review found EMDR to be comparably effective to trauma-focused cognitive behavioural therapy in reducing PTSD symptoms, which is a meaningful finding given how well-studied TF-CBT is.
Beyond PTSD, the picture is more nuanced but increasingly promising. Research suggests EMDR may be helpful for anxiety disorders, depression with traumatic roots, phobias, OCD, and chronic pain; conditions that often have distressing memories or early experiences at their core, even when that isn't immediately obvious. The EMDR International Association describes anxiety, depression, OCD, chronic pain, and addiction as conditions with emerging evidence for the approach.
It's worth being honest about the limits: the evidence outside PTSD is less robust, and NICE's current guidance is cautious about recommending EMDR for conditions beyond PTSD. Responsible EMDR therapists will be clear about what the research does and doesn't support for any given presentation.
One area that is sometimes misunderstood: EMDR is not only for people who have experienced what is commonly understood as a traumatic event; war, assault, accident. It is also used for what clinicians sometimes call small-t trauma: the accumulated experiences of emotional neglect, relational difficulty, shame, and the kind of painful childhood experiences that don't constitute a single dramatic incident but have nonetheless shaped how a person relates to themselves and the world. Our piece on emotional neglect and its long-term effects explores this territory, and the way that experiences without an obvious single event can be just as shaping as those that have one.
What to expect if you pursue EMDR
Finding a qualified EMDR therapist matters. In the UK, look for a therapist who is accredited by EMDR UK (the professional body that sets training and practice standards). Training in EMDR is substantial, and not all practitioners who describe themselves as using EMDR will be fully trained or accredited.
EMDR is typically delivered over a series of sessions, the number of which will depend on the complexity of what is being worked on. Single-incident trauma may be processed in a relatively small number of sessions. Complex trauma, or presentations involving multiple or early experiences, will generally require longer work. A good EMDR therapist will be upfront about this from the beginning.
It is also worth knowing that EMDR, particularly the processing phases, can be emotionally intense. The preparation phases of the protocol exist precisely to build the capacity to tolerate that, and a skilled therapist will not rush this. If you are considering EMDR and want a clearer picture of how the therapy process works more broadly, our piece on what actually happens in a therapy session is a good starting point.
EMDR is not a magic solution, and it is not for everyone. But for people whose distress is rooted in the way the brain has stored difficult experiences, it offers something that many other approaches don't: a way of working with memory itself, rather than only with the thoughts and behaviours that memory produces.
Interested in finding an EMDR therapist in south London?
Our directory lists experienced therapists and counsellors across Battersea and Lavender Hill, working with a range of approaches and presentations. Browse therapists at Smart Therapy.
