Bilateral stimulation (BLS) is a core technique in therapies like Eye Movement Desensitization and Reprocessing (EMDR) and Accelerated Resolution Therapy (ART), but the question remains: Why does BLS seem so effective in helping people heal from trauma? In this post, we’ll explore what BLS is, the theories behind its effectiveness, and why it works for so many people.
What is Bilateral Stimulation and How Is It Used in Therapy?
Bilateral stimulation refers to rhythmic movements or sounds that alternate between the left and right sides of the body or brain. This can include visual stimuli (like eye movements), physical movements (such as tapping), or auditory signals (alternating sounds). While the exact mechanism behind BLS isn’t fully understood, several theories focus on how BLS interacts with the brain’s natural processes for processing memory, emotion, and healing.
Theories Behind Why Bilateral Stimulation Works
*Bilateral Stimulation Mimics Brain Activity During REM Sleep
One of the most compelling theories suggests that BLS replicates the brain activity seen during rapid eye movement (REM) sleep. During REM, the brain processes emotional and procedural memories, integrating them in a way that reduces their emotional charge. Research has shown that the eye movements in EMDR produce brainwave patterns that closely resemble those of REM sleep, which is when our memories are reprocessed and emotions are integrated.
This theory suggests that BLS helps the brain reprocess traumatic memories by mimicking the natural processes of REM sleep. Rather than erasing traumatic memories, BLS may allow them to be reframed and integrated, reducing their emotional intensity over time. This could be why many individuals report feeling less distressed by past traumas after engaging in BLS-based therapies.
*Bilateral Stimulation Overloads the Brain’s Working Memory
Another popular theory posits that BLS may overload the brain’s working memory, which is responsible for temporarily holding and processing information. In therapies like EMDR, clients are asked to recall distressing memories while also focusing on alternating BLS, such as following the therapist’s fingers or listening to alternating sounds.
Because the brain can only process so much information at once, dividing attention between a traumatic memory and rhythmic bilateral stimuli may make it harder for the brain to maintain the vividness and emotional intensity of the memory. This results in a decrease in distress, helping the individual process trauma more effectively. Research supports this idea: tasks that divide attention, such as recalling a memory while engaging in a secondary task, can reduce the intensity and emotional charge of the memory.
*Bilateral Stimulation Promotes Memory Reconsolidation
Memory reconsolidation is a process through which memories can be altered when recalled. When a memory is retrieved, it enters a “reconsolidation window,” during which it is vulnerable to modification by new experiences or information. Some researchers believe that BLS facilitates this process, particularly in therapies like EMDR.
By recalling a traumatic memory while engaging in BLS, the therapist may help the client modify the emotional context of that memory. This could involve reframing the way the client feels about the traumatic event or gaining new insights that help reduce its emotional charge. The idea is that memories are malleable, and BLS serves as a catalyst for this reconsolidation, allowing the individual to reprocess the memory in a less distressing way.
Why BLS Works: The Bigger Picture
While these theories offer fascinating insights into how BLS may work, the effectiveness of this technique often goes beyond just one explanation. In my work I see BLS help bypass the overthinking that can keep clients stuck. I appreciate the way BLS allows clients to connect both the logical (left-brain) and emotional (right-brain) centers of the brain and their body, facilitating deeper processing and emotional integration. In my experience is something that talk therapy alone can struggles to achieve.
Conclusion
The rhythmic stimuli of BLS can break through emotional blockages, helping people heal in ways that are often inaccessible through verbal therapy alone. While the exact mechanisms behind why BLS works may still be debated, the results speak for themselves: it offers a unique way to help individuals process and heal from experiences. BLS can provide a hopeful way forward. As research continues, we may uncover even more about why BLS is so effective, but for now, its ability to facilitate emotional processing and memory reconsolidation makes it an invaluable tool in therapy.