The Science Behind EMDR: How It Works and Why

The Science Behind EMDR: How It Works and Why

When we experience distressing events, our brains sometimes struggle to process them properly. Eye Movement Desensitization and Reprocessing (EMDR) therapy helps our minds heal from these experiences. But how exactly does it work? This article explains the science behind EMDR in straightforward terms.

The Basics: What Happens in Our Brains During Trauma

Memory Storage Gone Wrong

Think about how you remember your birthday party last year versus how you might remember a car accident. The birthday memory probably feels distant and factual. You can recall it without feeling strong emotions. But memories of distressing events often feel different—they can feel fresh, intense, and overwhelming, as if they’re happening right now.

This difference occurs because traumatic or highly stressful experiences can overwhelm our brain’s normal information processing system. Instead of being stored as “past events” like regular memories, distressing experiences can get “stuck” in a raw, unprocessed form.

The Brain’s Filing System

Your brain has an amazing ability to take new experiences and connect them with existing knowledge. This helps you make sense of the world and learn from experiences. This system works through networks of connected memories, thoughts, and feelings.

For example, when you think about “dogs,” your brain might activate connections to:

  • Facts about dogs (they have four legs, they bark)
  • Personal experiences with dogs (your childhood pet, a dog that scared you once)
  • Emotions related to dogs (joy, fear, comfort)
  • Physical sensations (the feel of fur, the sound of barking)

When this system works well, new experiences get processed and filed away properly, connected to relevant information that helps you make sense of them.

When Processing Gets Stuck

During highly stressful or traumatic experiences, this processing system can become overwhelmed. Several factors contribute to this:

  • Stress hormones flood your system
  • Your brain prioritizes survival over memory processing
  • The emotional intensity overwhelms normal integration mechanisms

As a result, the memory gets stored in a fragmented, unprocessed state—disconnected from the broader context that would help make sense of it. These unprocessed memories contain the raw emotions, physical sensations, and negative beliefs from the original experience.

When something reminds you of the distressing event later, these unprocessed elements can be triggered, making you feel like you’re re-experiencing aspects of the original event rather than simply remembering it.

How EMDR Helps: The Adaptive Information Processing Model

EMDR therapy is based on the Adaptive Information Processing (AIP) model, developed by Dr. Francine Shapiro, who discovered EMDR in 1987. This model suggests that our brains have a natural healing capacity that can be activated to resolve psychological distress.

The Brain’s Natural Healing System

Think about how your skin heals after a cut. Your body naturally works to repair the damage unless something interferes with the healing process. The AIP model suggests that our minds have a similar natural ability to heal psychological wounds.

Just as a physical wound might need help to heal properly (cleaning, bandaging, stitches), psychological wounds sometimes need assistance to process properly. EMDR provides that assistance by helping the brain resume natural processing that got stuck.

Bilateral Stimulation: The Key Mechanism

The most distinctive feature of EMDR is bilateral stimulation—typically side-to-side eye movements, alternating tones, or tapping that stimulates both sides of the brain in a rhythmic pattern. But how does moving your eyes or listening to alternating tones help process traumatic memories?

Several theories explain how bilateral stimulation works:

1. Working Memory Theory

Our working memory has limited capacity—it can only hold so much information at once. When you recall a distressing memory while simultaneously focusing on bilateral stimulation, you’re essentially forcing your working memory to divide its resources.

This division makes the memory temporarily less vivid and emotional, creating a window where you can access the memory without being overwhelmed by it. This allows your brain to begin reprocessing the memory in a less distressing state.

2. REM-Like Processing

The side-to-side eye movements in EMDR resemble what happens during Rapid Eye Movement (REM) sleep, when much of our emotional processing and memory consolidation occurs naturally.

Some researchers believe EMDR may tap into similar mechanisms as REM sleep, essentially helping your brain process emotional memories the way it naturally would during sleep. This might explain why people often report new insights and perspectives emerging during EMDR sessions—similar to how solutions sometimes come to us in dreams.

3. Dual Attention Stimulation

EMDR requires you to simultaneously focus on internal distressing material while maintaining awareness of the present-moment bilateral stimulation. This dual attention helps you stay grounded in the present while accessing past memories.

This balance prevents you from becoming completely immersed in the traumatic memory (which can be retraumatizing) while still allowing enough access to process it. It creates a “foot in both worlds” experience that seems optimal for reprocessing.

4. Orienting Response

The bilateral stimulation may activate what’s called an “orienting response”—our brain’s automatic reaction to new stimuli in our environment. This response temporarily disrupts the anxiety associated with the traumatic memory and induces a relaxation response.

This relaxation allows the brain to access the memory network in a calmer state, making it easier to integrate new, more adaptive information.

What Brain Imaging Tells Us About EMDR

Modern brain imaging techniques have helped scientists understand the neurobiological changes that occur during and after EMDR therapy.

Brain Regions Affected by EMDR

The Amygdala

The amygdala acts as your brain’s alarm system, constantly scanning for threats. In people with unprocessed trauma, the amygdala often becomes hyperactive, triggering strong emotional and physical responses even to minor reminders of the traumatic event.

Brain scans show that successful EMDR treatment reduces amygdala activity, meaning the brain no longer reacts to reminders with the same intensity.

The Prefrontal Cortex

This region is responsible for rational thinking, planning, and emotional regulation. During traumatic recall, activity in the prefrontal cortex often decreases, making it harder to think clearly or regulate emotions.

After EMDR therapy, researchers observe increased activity in the prefrontal cortex when the person thinks about the previously traumatic material. This suggests improved ability to think about the experience rationally rather than just react emotionally.

The Hippocampus

The hippocampus plays a crucial role in organizing memories in context (when, where, and how events happened). Trauma can impair hippocampal functioning, contributing to fragmented, disorganized memories.

Studies show that EMDR therapy can increase hippocampal volume and improve its functioning, helping properly contextualize traumatic memories as past events rather than current threats.

Neurochemical Changes

EMDR therapy also appears to normalize levels of stress hormones and neurotransmitters:

  • Cortisol: Levels of this stress hormone often normalize after successful EMDR treatment
  • Norepinephrine: This “fight-or-flight” chemical typically shows reduced reactivity following EMDR
  • Serotonin and Dopamine: These “feel-good” neurotransmitters often show improved regulation after treatment

The Reprocessing Journey: What Happens During EMDR

Understanding what happens during EMDR processing helps explain the science behind its effectiveness.

Phase 1: Activation

First, you activate the memory network containing the distressing material. This includes:

  • The visual images associated with the memory
  • The negative beliefs you formed about yourself
  • The emotions connected to the experience
  • The physical sensations that arise when recalling it

This activation makes the memory network accessible for processing.

Phase 2: Desensitization

As bilateral stimulation continues while you hold the memory in awareness, several things typically happen:

  • Associations emerge: Your brain naturally begins connecting the targeted memory with other related memories, thoughts, and insights. You might suddenly remember related events or gain new perspectives.
  • Emotional shifts occur: The intensity of emotions typically changes, often decreasing but sometimes temporarily increasing as deeper material emerges.
  • Physical sensations transform: Bodily sensations often shift, move, or release during processing.
  • Cognitive insights develop: New understandings about the experience and yourself naturally emerge.

This process continues until the distress associated with the memory significantly decreases.

Phase 3: Installation

Once distress decreases, the focus shifts to strengthening positive beliefs about yourself related to the experience. For example, shifting from “I am helpless” to “I can handle difficult situations.”

The bilateral stimulation helps strengthen these new neural connections, essentially rewiring your brain’s response to the memory.

Phase 4: Integration

The final phase involves scanning your body for any remaining tension or discomfort related to the memory. Any residual physical sensations are processed with additional bilateral stimulation until the body feels calm when recalling the memory.

The Evidence: What Research Shows About EMDR

EMDR is one of the most researched psychotherapy approaches for trauma treatment. Here’s what the science tells us:

Effectiveness for PTSD

Multiple randomized controlled trials (the gold standard in research) show that EMDR therapy significantly reduces PTSD symptoms. The American Psychological Association, the World Health Organization, and the Department of Veterans Affairs recognize EMDR as an effective treatment for trauma.

Studies consistently show that 77-90% of single-trauma victims no longer meet the criteria for PTSD after just 3-7 sessions of EMDR therapy.

Speed of Results

Research indicates that EMDR often works more quickly than traditional talk therapies for trauma. This efficiency may be because EMDR directly targets the brain’s information processing system rather than requiring extensive verbal processing.

Long-Term Benefits

Follow-up studies show that the benefits of EMDR therapy typically maintain over time, with many people continuing to improve even after treatment ends. This suggests that EMDR activates a natural healing process that continues working.

Beyond Trauma

While initially developed for trauma, research now supports EMDR’s effectiveness for:

  • Anxiety disorders
  • Depression
  • Phobias
  • Grief
  • Pain conditions
  • Performance anxiety

This broader application makes sense when we understand that many psychological difficulties stem from unprocessed distressing experiences, not just major traumas.

Self-Administered EMDR: What We Know

Most research on EMDR involves therapist-led sessions. However, emerging evidence suggests that self-administered EMDR can be beneficial when used appropriately:

  • A 2013 study found that self-administered EMDR reduced anxiety symptoms in university students
  • Research on EMDR telehealth (remote sessions with minimal therapist involvement) shows promising results
  • Studies on EMDR-related techniques like the “butterfly hug” (a self-administered bilateral stimulation) show effectiveness for stress reduction

Self-administered EMDR appears most appropriate for:

  • Reinforcing previous therapist-led EMDR work
  • Processing milder distressing experiences
  • Managing everyday stress and anxiety
  • Building emotional resources

For complex trauma, severe symptoms, or major mental health conditions, therapist-led EMDR remains the recommended approach.

The Limitations: What Science Doesn’t Yet Fully Explain

While evidence strongly supports EMDR’s effectiveness, some aspects remain under investigation:

The Specific Role of Eye Movements

Some studies suggest that the bilateral stimulation is essential to EMDR’s effectiveness, while others indicate that the broader EMDR protocol might work even without this component. Research continues to explore exactly how and why bilateral stimulation contributes to healing.

Individual Differences in Response

Not everyone responds to EMDR in the same way or at the same speed. Scientists are still investigating the factors that influence individual responses, including:

  • The nature and timing of the traumatic experiences
  • Pre-existing neurobiological factors
  • Attachment history and relationship patterns
  • Current life stressors and support systems

Optimal Protocols for Different Conditions

While standard EMDR protocols exist, researchers continue to refine and adapt these for specific conditions and populations. The optimal approach may vary depending on the person and their unique circumstances.

Conclusion: The Science of Healing

EMDR therapy represents a fascinating intersection of neuroscience, psychology, and the brain’s natural healing abilities. By understanding how traumatic experiences disrupt normal information processing and how bilateral stimulation helps restore it, we gain insight into both the nature of psychological suffering and the remarkable capacity of our brains to heal.

The science behind EMDR continues to evolve, but the existing evidence strongly supports its effectiveness. Whether facilitated by a therapist or carefully self-administered, EMDR offers a powerful approach to processing distressing experiences and moving toward greater emotional wellbeing.

As you use the EmEase app, remember that you’re engaging with a scientifically-supported approach that works with your brain’s natural healing mechanisms. By understanding the science behind the process, you can approach your healing journey with greater confidence and awareness.