The science of bilateral stimulation and why it works

Bilateral stimulation (BLS) sounds complicated, but it’s really just alternating left-right stimulation — through eye movements, tapping, or sounds — to engage both sides of the brain.

This is the foundation of OEI therapy and why it evolved from EMDR (Eye Movement Desensitisation and Reprocessing) and newer approaches like the EMDR Flash Technique.

And here’s the thing.

There’s solid neuroscience behind why it works.

How bilateral stimulation affects the brain

When you experience trauma, your brain’s emotional center (amygdala) goes on full alert and your memory filing center (hippocampus) can go offline.

This means the memory doesn’t get stored properly — it stays stuck, unprocessed in the here and now, and you feel triggered AF.

Bilateral stimulation seems to activate the brain’s memory processing network.

Here’s what’s happening in your brain:

Calms the alarm system — Brain imaging studies show BLS lowers activity in the emotional center of your brain (the amygdala), reducing hypervigilance and emotional flooding. This is the main reason why you feel stuck. If brain is not calm, most things you try won’t work, things like talk therapy, etc.

Engages both hemispheres of the brain — BLS stimulates the left and right hemispheres alternately, creating balance and improving communication between them so they can work things out and not be in conflict.

Activates working memory — Moving your eyes or alternating taps uses up some of your brain’s working memory capacity, which gives the subconscious access to the distressing memory and integrate it into the past. The memory gets filed in away, so it feels “in the past” rather than happening right now.

Supports reconsolidation — The memory becomes less vivid and less emotional as it gets processed, integrated, and reconsolidated. The emotional sting of the memory fades.

Why bilateral stimulation feels regulating

If you’ve ever gone for a long walk and felt calmer afterwards, you’ve already experienced a form of natural bilateral stimulation.

Walking rhythmically, alternating left-right steps, can help regulate your brain and body.

BLS used in trauma therapy works on the same principle — it brings the nervous system back into balance. Many clients report feeling grounded, calm, even sleepy after a session.

OEI Therapy: a gentler application of BLS

OEI Therapy has been evolved from EMDR and builds on the science of bilateral stimulation but with a big difference— you don’t have to focus on the traumatic memory.

You don’t have to remember to recover.

This enables the brain to process the trauma without overwhelming you with emotion of revivification that occurs when you think or talk about the distressing experience.

EMDR Flash is also effective. Research by Manfield et al. (2021) found that Flash Technique rapidly reduced the emotional intensity and vividness of disturbing memories, while being rated as more pleasant and less distressing than traditional EMDR.

Who can benefit from bilateral stimulation

OEI Therapy isn’t just for PTSD — it’s used for anxiety, grief, phobias, and even performance blocks.

Because it works at the level of your brain and body, it’s helpful when talking about trauma isn’t enough or even feels retraumatizing.

Bilateral stimulation works because it helps your brain integrate memories that are stuck in the here and now. BLS calms your alarm system, and put the past where it belongs — in the past.

Approaches like OEI therapy and EMDR Flash Technique make the process even more tolerable by working with visual pathways to healing and can help you heal faster and with less distress.

Let’s connect.