The Science Behind EMDR: How Does EMDR Therapy Work?
If you’ve heard about EMDR therapy, you may have wondered: How can moving your eyes—or listening to sounds that alternate between your left and right ears—possibly help with trauma?
It can sound a little strange at first.
But EMDR (Eye Movement Desensitization and Reprocessing) isn’t hypnosis, and it isn’t about erasing memories. You remain awake, aware, and in control throughout the process.
The simplest way I explain it to my clients is this:
EMDR isn’t about forcing anything—it’s about letting your brain finally finish what it started. Sometimes when something overwhelming happens, your system doesn’t get the chance to fully process it. EMDR helps your brain move it through so it feels less intense and in the past.
There is now substantial research supporting EMDR as a treatment for PTSD and trauma-related symptoms, although researchers are still studying exactly why it works. The VA’s National Center for PTSD notes that EMDR is recommended in multiple major clinical practice guidelines for PTSD. [1]
So, let’s talk about what may actually be happening in your brain—and what an EMDR session with me looks like.
First: What Is EMDR?
EMDR stands for Eye Movement Desensitization and Reprocessing.
It was originally developed to treat traumatic memories. Rather than simply talking about what happened, EMDR asks your brain to briefly connect with pieces of an experience—such as an image, thought, emotion, or body sensation—while you simultaneously engage in bilateral stimulation (BLS).
Bilateral simply means left and right.
BLS can involve:
Moving your eyes from side to side
Listening to alternating tones through headphones
Alternating tapping on the body
Other structured left-right stimulation
I often use auditory bilateral stimulation in my telehealth EMDR sessions with clients throughout Tampa and Florida.
The bilateral stimulation is only one component of EMDR. EMDR is actually a structured psychotherapy consisting of eight phases, including history-taking, preparation, assessment, desensitization, installation of adaptive beliefs, body scan, closure, and reevaluation. [2]
So...What Is Happening in the Brain During EMDR?
This is where things get interesting.
We know considerably more about EMDR than we did when it was first developed, but scientists have not established one single definitive mechanism that explains everything EMDR does.
Several theories may help explain its effects.
Your Brain Is Designed to Process Experiences
Most everyday experiences get integrated into the larger story of our lives.
You can remember them without necessarily re-experiencing them.
Traumatic or highly distressing experiences can be different.
According to the Adaptive Information Processing (AIP) model underlying EMDR, some distressing experiences may remain inadequately processed and stay connected to the emotions, physical sensations, and beliefs associated with the original experience.
That can help explain why something happening today can suddenly make you feel like you are right back in something that happened years ago.
You intellectually know:
That was then.
But your nervous system may respond:
It’s happening again.
EMDR attempts to help that memory become more adaptively integrated so that you can remember what happened without your brain and body responding as though it is still happening now.
The Working Memory Theory: Why the Left-Right Stimulation May Matter
One of the better-supported explanations for part of EMDR’s effect is called the working memory hypothesis.
Your working memory has limited capacity.
Imagine trying to hold a distressing image clearly in your mind while simultaneously completing another task that requires attention.
It becomes harder to do both at full intensity.
During EMDR, you may briefly bring up part of a distressing memory while your brain is also following alternating sounds or eye movements.
Research suggests that this competing demand on working memory may reduce the vividness and emotional intensity of distressing memories. A systematic review of proposed EMDR mechanisms found reasonable empirical support for the working-memory explanation, while also emphasizing that research into exactly how EMDR works is still developing. [3]
A meta-analysis examining eye movements also found evidence that they contributed to reductions in the vividness and emotionality of memories. [4]
This doesn’t mean the memory disappears.
The goal is for the memory to become something you remember rather than something you continue to relive.
EMDR Is More Than “Calming Down”
One of the things I find fascinating about EMDR is that clients often begin making connections that we did not deliberately plan.
A memory may lead to another memory.
A body sensation may change.
A belief that once felt completely true may suddenly feel less convincing.
Someone might begin with:
“It was my fault.” And eventually arrive at: “I was a child. I couldn’t have been responsible for that.”
Or:
“I’m not safe.” may begin shifting toward: “I survived it, and I am safe now.”
I will not tell you what you should believe. Your brain is making the connections. That distinction is important.
Sometimes EMDR Changes How You See Other People
This is an aspect of EMDR that I think deserves more discussion.
As memories become less emotionally charged, you may begin seeing past and present relationships differently.
Sometimes you recognize:
I was carrying responsibility that was never mine.
What happened actually wasn’t okay.
I don't have to keep proving myself.
Their reaction belongs to them.
I can trust myself.
In that sense, EMDR can sometimes help you see a situation more clearly—not necessarily “the truth” in some absolute sense, but with less interference from fear, shame, guilt, or old survival responses.
And yes, that can change relationships.
You may develop stronger boundaries.
You may stop automatically apologizing.
You may recognize unhealthy patterns.
You may become less reactive to someone who previously triggered you.
You might also develop more compassion for someone once you are no longer experiencing them through the lens of an old wound.
Healing can change relationships because healing can change your relationship with yourself.
What Does an EMDR Session Actually Look Like?
We don't necessarily jump straight into the hardest thing that has ever happened to you.
Good EMDR treatment involves preparation.
EMDRIA—the EMDR International Association—describes EMDR as an eight-phase therapy. EMDRIA sets professional standards and requirements for EMDR training and continuing education. [2,5]
I am EMDRIA-trained, meaning my EMDR training followed EMDRIA-approved standards for foundational EMDR education, supervised practice, and consultation.
Before beginning reprocessing, we spend time understanding:
What brings you to therapy
Your history and current symptoms
Experiences that may be connected to what is happening now
Your existing coping skills
How your nervous system responds when activated
Whether you have enough stability and resources to begin processing safely
We also develop grounding and regulation strategies. Then we identify a specific target.
Choosing an EMDR Target
A target may be a traumatic event, but it doesn't always have to be the stereotypical “big trauma.”
It might be:
A car accident
A medical procedure
The death of someone you love
A humiliating experience
Childhood criticism
Betrayal
Bullying
A frightening event
A relationship experience
Something that left you feeling powerless, unsafe, ashamed, or responsible
A future situation that creates intense anxiety
We usually identify several pieces of the target, including:
The image or moment that represents the worst part
The negative belief connected to it
What you would rather believe about yourself
The emotions you notice
Where you feel it in your body
How disturbing it feels now
Then we begin bilateral stimulation.
What Happens During the Bilateral Stimulation?
I may ask you to bring up the target briefly and then begin the bilateral stimulation.
After a set, a series of bilateral stimulation (BLS) passes completed continuously before pausing, I may simply ask:
“What do you notice now?” And then we follow what comes up.
You don't have to make anything happen.
You don't have to figure out the “right” answer.
You don't have to analyze every thought.
You notice.
We do another set.
You notice again.
Sometimes the original image changes. Sometimes another memory appears. Sometimes emotions rise and then decrease. Sometimes the change is primarily physical—you suddenly realize the tightness in your chest, jaw, throat, or stomach is gone.
And sometimes your brain produces a realization you weren't expecting.
That is part of why I often tell clients:
Just notice, and let your brain do what it needs to do. Allow yourself to get out of the way of the process.
What Do I Need for Auditory EMDR?
For the auditory bilateral stimulation I use during telehealth EMDR sessions, the setup is pretty simple.
You generally need:
Headphones or earbuds that play true stereo sound
A reliable internet connection
A computer, tablet, or appropriate device for the telehealth/EMDR platform
A private place where you feel physically and emotionally safe
Enough uninterrupted time for the session
Water nearby
A comfortable place to sit
Ideally, some time after the session because you may be tired and need to rest
The headphones matter because the sound needs to alternate correctly between the left and right ears.
Before processing, we test the bilateral audio together so you can confirm that you hear it moving from one side to the other.
You are still able to hear me and communicate with me throughout the process.
How Long Does EMDR Take?
It varies..
Some specific targets can shift surprisingly quickly. Complex trauma, developmental trauma, repeated experiences, or multiple interconnected targets generally require more time.
EMDR is not a race.
The goal isn't to get your distress to zero as fast as possible. In fact, your distress number may never get to 0.
The goal is meaningful, tolerable processing that your nervous system can integrate.
I have now used EMDR with dozens of clients, and in my clinical experience I have seen some level of positive movement with every client I have treated using EMDR.
That does not mean every person responds the same way, every target completely resolves, or EMDR works for everyone. Therapy outcomes are individual.
What I have repeatedly witnessed, though, is movement—sometimes dramatic and sometimes subtle—in distress, body sensations, beliefs, emotional reactivity, or the way a person understands what happened to them.
Is EMDR Only for PTSD?
PTSD and trauma are where the evidence for EMDR is strongest.
The VA's National Center for PTSD identifies EMDR as one of the trauma-focused psychotherapies recommended by major PTSD treatment guidelines. [1]
But clinicians and researchers have also studied EMDR for other concerns.
Trauma and PTSD
EMDR has its strongest research base for PTSD and traumatic experiences.
If past experiences continue to show up as intrusive memories, avoidance, hypervigilance, emotional reactivity, negative beliefs, or physical activation, you can learn more about my trauma therapy in Tampa and throughout Florida.
Anxiety
EMDR may also be useful when anxiety is strongly connected to distressing memories, learned fears, panic, phobias, or experiences that taught your nervous system that something is dangerous.
A meta-analysis of 17 randomized trials involving 647 participants found reductions in anxiety, panic, phobia, and behavioral/somatic symptoms, although more research on long-term outcomes is needed. [6]
Learn more about anxiety therapy in Tampa and Florida.
Depression
Sometimes depression isn't only about what is happening today.
It may be connected to experiences that created deeply held beliefs such as:
I'm not good enough.
I'm a failure.
I'm unlovable.
Nothing I do matters.
Learn more about depression therapy in Tampa and throughout Florida.
Grief and Loss
Grief itself is not something that needs to be erased or “fixed.”
You don't EMDR away love.
But sometimes grief becomes intertwined with traumatic images, guilt, helplessness, medical experiences, circumstances surrounding a death, or a moment your brain seems unable to move beyond.
In those situations, EMDR may be incorporated into grief treatment when clinically appropriate.
Learn more about grief therapy in Tampa and Florida.
Will I Forget What Happened?
No.
A successfully processed memory is still a memory. What often changes is your relationship to the memory.
Instead of:
“It's happening, I’m in danger.” your nervous system can begin recognizing: “It happened, and I’m safe now.”
That one change can be enormous.
The memory may become less vivid or emotionally intense. Your body may stop reacting as strongly. The belief attached to the experience may change.
You don't have to forget your memories to stop living inside them.
Is EMDR Evidence-Based?
Yes—particularly for PTSD.
At the same time, I think it's important to talk about EMDR research accurately rather than presenting it as magic.
Research supports EMDR for PTSD, and it is included in multiple major clinical practice guidelines. [1] Research has also investigated EMDR for anxiety, depression, phobias, and other mental health concerns, with promising findings in some areas but a smaller and less definitive evidence base than exists for PTSD. [6–8]
And while we have plausible and increasingly researched explanations—including working-memory effects and physiological/neurobiological changes—scientists are still studying exactly how the different components of EMDR produce therapeutic change. [3]
That's actually normal in psychotherapy. We can know that a treatment helps before every part of its mechanism has been completely mapped.
EMDR Therapy in Tampa and Throughout Florida
I provide EMDR therapy through telehealth for clients in Tampa and throughout Florida.
As a Florida Licensed Mental Health Counselor, Art Therapist, and EMDRIA-trained EMDR therapist, I integrate EMDR with other approaches depending on what each person needs. EMDR isn't appropriate for every client at every moment, and preparation and stabilization are important parts of the process.
If you understand why you feel the way you do, but your body reacts as though the past is happening now, EMDR may be a good modality for you.
Because sometimes insight isn't the missing piece. You may understand what happened, but your nervous system just hasn't realized that it's over.
📚 References
U.S. Department of Veterans Affairs, National Center for PTSD. Eye Movement Desensitization and Reprocessing for PTSD. The VA summarizes the evidence for EMDR and its recommendations across major PTSD clinical practice guidelines.
EMDR International Association (EMDRIA). EMDR Basic Training. EMDRIA describes the eight phases of EMDR therapy and the standards for EMDRIA-approved basic training.
Landin-Romero, R., Moreno-Alcazar, A., Pagani, M., & Amann, B. L. (2018). How Does Eye Movement Desensitization and Reprocessing Therapy Work? A Systematic Review on Suggested Mechanisms of Action. Frontiers in Psychology, 9, 1395.
Lee, C. W., & Cuijpers, P. (2013). A meta-analysis of the contribution of eye movements in processing emotional memories. Journal of Behavior Therapy and Experimental Psychiatry, 44(2), 231–239.
EMDR International Association (EMDRIA). EMDR Training and Education / EMDRIA FAQs. EMDRIA is a nonprofit membership and credentialing association that establishes standards and requirements for EMDR training and continuing education.
Yunitri, N., Kao, C. C., Chu, H., et al. (2020). The effectiveness of eye movement desensitization and reprocessing toward anxiety disorder: A meta-analysis of randomized controlled trials. Journal of Psychiatric Research, 123, 102–113.
Yan, S., Shan, Y., Zhong, S., et al. (2021). The Effectiveness of Eye Movement Desensitization and Reprocessing Toward Adults With Major Depressive Disorder: A Meta-Analysis of Randomized Controlled Trials. Frontiers in Psychiatry.
Cuijpers, P., van Veen, S. C., Sijbrandij, M., Yoder, W., & Cristea, I. A. (2020). Eye movement desensitization and reprocessing for mental health problems: A systematic review and meta-analysis. Cognitive Behaviour Therapy, 49(3), 165–180.
