Beyond Deep Sleep: a Breakthrough at REPLAY Cardiff
Not too long ago, our science team had the pleasure of attending, and presenting at, the REPLAY conference at Cardiff University in Wales. This recurring international meeting brings together leading sleep scientists from across Europe and beyond, all focused on one central theme: the deep and fascinating interplay between sleep and memory. And with good reason! We shared some exciting previews on a novel direction our work is taking: one that could reshape how we think about emotional memory.
The response? Energized, inspired, and future-focused. And at the center of it all was our own Lucia Talamini, who presented a powerful and visionary look at what’s next in the field.
Highlights from REPLAY
Before we dive into Lucia’s talk, here’s a quick look at just some of the brilliant research that set the stage:
Marcel Kehl (University of Oxford) - presented striking evidence that individual human neurons, specifically those tuned to images during learning, reactivate during non-REM sleep—most often during sharp-wave ripples, a brain pattern long associated with memory consolidation. It was beautiful to see this research reinforce a long-standing hypothesis: that these ripples play a crucial role in stabilizing memories during sleep.
Michael Hahn (University Medical Center Tübingen) - shared insights on how different brain regions process information during sleep using advanced mathematical techniques. His work highlighted that patterns in humans diverge significantly from rodent models—a compelling reminder that sleep functions may be uniquely tuned in humans. This species-specific perspective further underscores the importance of human-focused research, especially when translating findings into therapeutic applications.
While these talks illuminated critical mechanisms in non-REM sleep, Lucia’s contribution asked a bold new question:
"What if the same precision we use to strengthen your deepest stages of sleep could be applied to REM sleep, helping the brain reshape emotional memories from within?"
DeepSleep, Deepens Impact: Introducing REM Phase Targeting
While Deep Sleep Technologies focuses on tools that deepen sleep and enhance memory consolidation during slow-wave sleep, we’ve always known that our method holds potential far beyond that domain. One area we identified early on as deserving a central place in direct-impact sleeptech is REM sleep. That’s why we’ve tailored our closed-loop method to precisely target specific phases of theta oscillations—the dominant brain waves of REM.
Why does this matter?
Because REM sleep plays a critical role in the emotional processing of memories. And for the first time, we now show that by delivering gentle, phase-locked sound cues during REM sleep we can causally influence the emotional tone of a memory, without disrupting its factual content.
“In short: this means there are possibilities that neurostimulation might help dial down the emotional "charge" of a traumatic memory, while keeping the memory itself intact!”
A Brief Glimpse Into the Study
During the study, healthy students took part in a series of overnight, lab-based experiments. To begin, each participant underwent a controlled fear-conditioning protocol, where neutral sounds were paired with mild wrist shocks and corresponding images. This setup was crucial—it allowed us to test whether the emotional tone of a memory (in this case, the negative charge added by the shock) could be modulated by our neurostimulation approach. Following the conditioning phase, participants went to sleep wearing a high-density EEG cap to monitor brain activity throughout the night.
(Curious what that EEG cap looks like? You can check out the video on our participation page)
Once they reached REM sleep, a subset of these participants received acoustic memory cues delivered in real-time during either the ascending or descending phase of their own theta oscillations, using our patented closed-loop modelling approach. A third group received no stimulation. Throughout the night, participants were monitored across multiple sleep cycles, with REM sleep stages repeatedly recorded and stimulated. After each REM episode, they were awakened to report their dreams (see figure below).
In the morning, participants completed a memory and emotional recall task. The results so far?
- Neurostimulation effect - the emotional responses to conditioned stimuli were significantly reduced when neurostimulation was applied.
- Memory accuracy - this reduction occurred without any loss in memory accuracy.
- Timing - the effect was observed across both targeted stimulation phases, suggesting a broader and more robust window for safe and effective intervention than previously thought.
Where This Is Heading
This study marks a major leap forward, not just for our own research team, but for the entire field of sleep-based intervention. It demonstrates that REM sleep is not just a passive dream stage, but a dynamic window where emotional memory can be safely reshaped using precisely timed cues.
And perhaps even more exciting: it shows that DeepSleep’s technology isn’t confined to deep sleep. With our the right algorithm and expertise, we can enter REM and guide the mind—gently, safely, and effectively.
We’re not just here to make sleep deeper. We’re here to make it smarter. More adaptive. A precision tool that supports your emotional health, resilience, and recovery in ways we’re only beginning to unlock. The journey is just getting started.