The Science Behind EMDR: Understanding How Bilateral Stimulation Facilitates Healing
Lexie Glisson • February 20, 2025

Eye Movement Desensitization and Reprocessing (EMDR) therapy has helped countless individuals heal from trauma, anxiety, and other emotional struggles. While EMDR is widely known for its ability to transform lives, many people don’t fully understand the science behind how it works. In this blog, we’ll dive into the neuroscience of EMDR and explain in simple terms how bilateral stimulation—the key element of the therapy—facilitates healing by processing distressing memories.


What is Bilateral Stimulation in EMDR?


At the heart of EMDR therapy is a process called bilateral stimulation (BLS). During EMDR sessions, the therapist guides the client to recall a distressing memory while engaging in a form of BLS, which typically involves eye movements, tapping, or auditory tones that alternate between the left and right sides of the body or brain. This bilateral stimulation mirrors the natural rhythms that occur during Rapid Eye Movement (REM) sleep, which is known for its role in memory processing and emotional regulation.


So, what does all of this have to do with healing? Let’s take a look at how these brain-based mechanisms work.


How Does Trauma Affect the Brain?


Our brains are powerful organs, but when we experience trauma, our neural pathways can become “stuck” in a state of high emotional activation. This means that memories related to traumatic events often get stored in the brain in an incomplete or fragmented way. As a result, when we try to recall these memories, we can become overwhelmed by the intense emotions attached to them.


In normal circumstances, the brain is able to process memories and integrate them into our understanding of the world. However, during trauma, the emotional response can be so intense that the brain’s natural processing system becomes overwhelmed, and the memory remains “stuck” in the emotional brain, which can lead to symptoms like flashbacks, nightmares, and emotional triggers.


How Does Bilateral Stimulation Help the Brain Process Trauma?


The process of bilateral stimulation helps to “unlock” this stuck memory by re-engaging the brain’s natural processing systems. Here’s how it works:


  1. Stimulating Both Sides of the Brain: Bilateral stimulation involves activating both hemispheres of the brain simultaneously. The left hemisphere is typically responsible for logic, language, and reasoning, while the right hemisphere governs emotions, imagination, and creativity. By stimulating both sides, BLS helps the brain process trauma in a more balanced way, integrating the emotional and cognitive aspects of the experience.
  2. How Does Bilateral Stimulation Mimic REM Sleep? During sleep, particularly in the REM stage, our brains naturally process emotional memories and integrate them. Bilateral stimulation in EMDR mimics the brain activity that occurs during REM sleep, helping the brain process and reframe traumatic memories without needing the client to relive the trauma in detail. This makes EMDR different from traditional talk therapy, where clients often have to retell their traumatic experiences over and over again.
  3. Can Bilateral Stimulation Reduce Emotional Intensity? By engaging both sides of the brain and activating natural memory processing systems, bilateral stimulation helps to reduce the emotional intensity of distressing memories. It’s as if the brain is able to file away these memories in a way that’s less distressing and more manageable, making it easier for the individual to move on with their life.
  4. Does Bilateral Stimulation Rewire Neural Pathways? The more a memory is processed through bilateral stimulation, the more the brain’s neural pathways are rewired to store the memory in a less emotionally charged way. Over time, this reduces the triggers and negative associations that come with the trauma, leading to emotional relief.


What Does Research Say About the Neuroscience of EMDR?


Studies have shown that EMDR is a highly effective treatment for trauma and PTSD, and much of its success can be attributed to the way bilateral stimulation influences the brain. For example, research conducted by Dr. Francine Shapiro, the founder of EMDR, revealed that bilateral stimulation has a direct impact on the limbic system, which is the part of the brain responsible for processing emotions.


One study published in the Journal of Traumatic Stress found that after just a few sessions of EMDR, people with PTSD showed significant reductions in the activation of the amygdala—the part of the brain that controls the “fight or flight” response. As the amygdala calms down, it becomes easier for individuals to process memories without the intense emotional reactions that often accompany trauma.


Additionally, functional MRI (fMRI) scans have shown that EMDR significantly changes how the brain processes traumatic memories. Researchers have found that EMDR increases prefrontal cortex activity, which is responsible for executive functions like decision-making and emotional regulation. This suggests that EMDR doesn’t just calm the emotional brain; it helps people make sense of their traumatic memories in a way that reduces their impact on day-to-day life.


Why Does EMDR Work So Well for Trauma?


Trauma can disrupt normal brain function, especially when the event is so distressing that it prevents the brain from fully processing the experience. What sets EMDR apart from other therapies is that it doesn’t just work on the emotional level—it helps the brain reorganize the way it stores and processes memories. By using bilateral stimulation, EMDR enables the brain to reprocess traumatic memories in a way that makes them less emotionally charged, helping individuals move from a state of survival to a state of healing.


How Can I Understand EMDR in Simpler Terms?


Think of your brain like a computer. When you experience a trauma, it’s like downloading a file that is incomplete or corrupted. Your emotional brain is trying to process that file, but because it’s not functioning correctly, the file gets stuck and causes problems.


Bilateral stimulation is like hitting the “refresh” button on your computer. It reboots the system, allowing the brain to reprocess and fix the corrupted file (the traumatic memory). Once the system is working properly, the file can be stored in a way that no longer causes distress.


Final Thoughts


The science behind EMDR therapy reveals that its success is rooted in the brain’s ability to process and rewire traumatic memories with the help of bilateral stimulation. By engaging both hemispheres of the brain and mimicking the brain’s natural REM sleep processes, EMDR provides a powerful way to heal from trauma, anxiety, and other emotional struggles.


If you’re curious about how EMDR could work for you, or you want to learn more about the science behind this transformative therapy, reach out today to schedule a consultation. Healing is possible, and EMDR might just be the key to unlocking your path to recovery.


By Lexie Glisson March 2, 2026
The Immediacy of Love: An Animas Quest into the More Than Human World I recently returned from two weeks in the Arizona wild that felt less like a trip and more like a tectonic shift of the self. It began with retaking the Equilateral (EMDR + Equine Assisted Therapy) training. This was a time of stripping back the layers to re-anchor into the wisdom of my body and the silent, honest presence of horses. But the grounding was only the preparation for the underworld descent of the Animas Valley Institute intensive: Deep Imagination. Somatic Healing and the Power of the Animal Body The transformation began the moment I closed my eyes on my first night in Arizona. I dreamt I was in the wild, surrounded by hundreds of cats. Their bodies were low, their eyes tracking me, stalking me like prey. I felt a familiar timidity, a fear that these wild beings could turn and attack at any moment. But then, the atmosphere shifted. The cats began rubbing against my legs, brushing past me, and purring with a deep, vibrating resonance. I felt caught between a cautious need to move slowly and a sudden, overwhelming realization: maybe they are just deeply relational. What followed was a sensation I feel I’ve been waiting my whole life for. It was a feeling of euphoria and a primal, erotic charge. It was a deep longing and desire finally being met. This dream became the blueprint for my time in the canyon. It taught me how to move through the world not as a spectator, but as an animal body, listening for the shimmering conversation between the hunter and the beloved. Transforming Fear into Relationship through Deep Imagination As I moved deeper into the canyon, the Wild Other changed its shape. I carried a second dream of being chased by a rattlesnake, paralyzed by the strike. With the help of a guide, I entered the somatic heart of that fear. I allowed my spine to elongate, stretching tall while my feet rooted into the earth. From this place of animal strength, I was able to turn and meet the snake’s gaze. In that eye-to-eye contact, the threat transformed into a relationship. I felt a deep, strange longing to be inhabited by this being, to allow the snake’s fluid, ancient power to become my own. Finding Flow and Softening in the More Than Human World Later, during a solo wander in the heat of the canyon, I found a deep bend in the river that moved in the exact, undulating shape of a serpent. I gave myself to it. I let the Snake River take me downstream, over and over. Each time, the challenge was the same: How soft can I get? I practiced softening every muscle, letting go of the ego’s need to control, allowing the current to devour my resistance. I wasn't just swimming. I was practicing the immediacy of love, a total, defenseless presence to the flow of life. The Practice of Reciprocity and Sacred Movement To honor these encounters, I entered into a silent ceremony. I offered the movement of my own body as an expression of deep respect and gratitude to the wild cat and the rattlesnake who had guided me. For four minutes of uninterrupted, silent movement, I let my body speak back to the canyon. In that dance, I wasn't just observing nature. I was offering myself to it. It was an act of reciprocity, a way to say, “I see you, I thank you, and I am here.” Moving from Ego to Intuition in the Wild The ego, however, is a persistent marcher. After the river, my thinking mind decided I needed to reach a specific, noble spot further up the canyon. I fought the current, ignoring my intuition three times as the walking grew harder. It took a prickly, thorned branch catching my skin to stop me dead in my tracks. When I finally surrendered and turned around, I saw the beauty I had been marching past: cottonwood fluff drifting like snow through the golden light. As I walked back downstream, the moment my mind drifted back to my noble goal, I tripped. I looked down and realized I was standing exactly where I had started, at the bend of the Snake River. And there, to my left, was the answer to my journey. I had asked the snake how I could stay connected to its power. There stood a tree with webbed roots , the exact image from my internal vision. Wholeness and the Immediacy of Love I am remerging from the canyon with a new understanding of wholeness. It is not a solo achievement or a destination we march toward. It is a collective recognition of the More Than Human world. We heal the long severance from our souls when we refuse to look away from the stalking cat, the striking snake, or the divine gift in another’s eye. When we stop trying to conquer the wild and instead allow ourselves to be devoured by its beauty, the gates of the kingdom swing wide.  Salvation is not a distant destination. It is the euphoria of the purr and the softening of the spine. It is the immediacy of love
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By Lexie Glisson January 31, 2026
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