Beyond Dreams: How REM Sleep Rewrites Emotional Memory at the Singapore World Sleep Congress 2025
This week, Singapore becomes the world’s capital of sleep science as the World Sleep Congress 2025 opens its doors. Researchers, innovators and clinicians from every corner of the world are gathering to exchange ideas and share their latest discoveries. Amid this wide-ranging program, one theme particularly stands out: REM sleep. Long understood as the stage where our most vivid dreams reside, it is now stepping into the spotlight for its critical role in shaping emotional memory – deciding what we keep, what we let go of, and how these memories feel by the time morning arrives.
Helping to guide this conversation is our own Dr. Lucia Talamini (CSO & founder of DST), serving as co-chair of a symposium alongside Prof. Gina R. Poe (advisory council member of DST). Both contribute not only as leaders but also speakers: Poe presents her research on the cell-level dynamics that drive REM, while Talamini shares her study on how REM stimulation can reshape the emotional weight a memory carries.
Joining them on stage are Dr. Tianqi Di, Postdoctoral Fellow in Professor X. Hu’s Lab at the University of Hong Kong, and Dr. Masanori Sakaguchi, Associate Professor and Principal Investigator at the International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba. Together with Poe and Talamini, they cover the spectrum of perspectives: from behavior to cells, circuits, and interventions.
At the center is a powerful question: how does REM help us manage fear, strengthen memories, and even soften their emotional edge? Research circle this puzzle from every angle, hinting at a story that stretches across behavior, cells, neural ensembles, and even real-time interventions — offering just a glimpse of the many layers at play.
"How does REM help us manage fear, strengthen memories, and even soften their emotional edge?"
Gina Poe: soma–dendrite coupling and decoupling as REM’s memory editor
Poe’s team looks at REM on the cellular scale. They study tiny hippocampal cells called oriens-lacunosum moleculare (O‑LM) interneurons, which decide whether the soma and the dendrites of memory neurons are coupled or decoupled.
The aim: examine whether this decoupling during REM is essential for refining emotional memory.
The findings: when decoupling is blocked, memories blur and fear spills too broadly into places it doesn’t belong. Poe demonstrates that REM’s coupling/decoupling mechanism acts like a fine-tuned editor, keeping our emotional memories sharp and well‑defined.
Masanori Sakaguchi: adult-born neurons and the timing of theta rhythms
Sakaguchi turns to brain circuits. His team investigates adult-born neurons (ABNs), a small population of cells that emerge throughout adulthood and closely track REM’s theta oscillations. In the study, researchers used a fear conditioning paradigm: a method where they link a safe context to a negative stimulus, like a mild shock. They then tag the neurons that become active and switch them on or off during REM to reveal their role in consolidating fear memory.
The aim: test if reactivation of these cells is needed for consolidating memory.
The findings: reactivating as few as three ABNs kept the memory alive, and silencing them made it vanish. Timing proved critical — the neurons had to fire in sync with a specific phase of theta rhythms — which shows that stable emotional memory relies on precise timing.
Tianqi Di: REM sleep as a precision filter against fear generalization
Di zooms out to behavior. Participants go through similar fear‑conditioning: a method where a harmless cue is linked to a mild unpleasant stimulus (linking a harmless cue with a mild unpleasant stimulus) and then face different types of sleep deprivation: early‑night (mostly NREM), late‑night (mostly REM), total, or none.
The aim: Di tests how REM-rich sleep versus NREM-rich sleep shapes fear generalization.
The findings: REM doesn’t just lock in fear memories — it shapes their boundaries. When REM stays intact, fear remains tied to its true source. When REM is lost, fear responses spill over into safe contexts. This work shows that REM’s frontal theta waves act like a precision filter, protecting us from overgeneralized fear and offering clues to why disrupted REM links to anxiety and PTSD.
Lucia Talamini: real-time REM stimulation to weaken fear memories
Talamini drives the discussion into application by testing real‑time intervention. Healthy subjects take part in a series of overnight lab studies. They go through a classical fear conditioning paradigm — learning to associate neutral sounds with mild wrist shocks and corresponding images — and then sleep while researchers record their brain-waves. During REM, a closed‑loop system plays sound cues timed to theta waves. Some cues match the rising phase, some the falling phase, others none.
The aim: test if such stimulation changes the emotional weight of memory.
The findings: REM stimulation weakened fear responses while preserving memory accuracy. This phase‑locked method uses the same technology that DeepSleep applies for deep sleep (NREM3) stimulation. Talamini’s work demonstrates that we can safely reshape emotional memories during REM, opening the door to future therapeutic use.
Why protecting REM sleep matters for everyday life
The symposium’s fresh insights into REM sleep reach far beyond the lab — they suggest why REM matters for you. Protecting your REM may not only help you feel rested, it can also support the brain’s ability to process emotions, contribute to mental well‑being, and open promising directions for therapies and technologies that could improve care in the future.
The good news? Supporting your REM sleep doesn’t have to be complicated:
Protect those “late night hours”: The brain mostly enters REM during the second part of the night so try to get enough sleep so that you allow your brain to reach this stage.
Keep the evenings calm: practicing calming routines (e.g. brief meditation sessions) before bed allows your body to turn on a “restorative” mode where REM truly shines.
How these insights brighten the future
Towards personalized interventions: if fear over-generalization can be traced back to REM theta oscillations and interneuron dysfunction, then neurostimulation could be tailored to restore “healthy decoupling” in each person.
Linking well-being and sleep science: This research highlights pathways that support emotional balance and resilience, while also offering clinical perspectives. By identifying early targets, it shows how healthy REM can help prevent stress from escalating into anxiety or PTSD, creating benefits for both everyday wellbeing and clinical care.
Making quality sleep accessible: As sleep technology finds its way into everyday consumer devices, the kind of precision once reserved for clinical settings is becoming part of daily life. This shift means that restorative, high‑quality sleep is no longer a luxury — it is becoming accessible for everyone.
Across behavior, brain cells, neural ensembles and real-time interventions, the symposium delivered one clear message once more:
“Sleep is no longer just a passive state; it’s becoming a domain where science gives us unprecedented control over recovery, resilience, and health.”
What this means for Deep Sleep Technologies
For DST, these findings highlight the next frontier in our mission: translating advanced sleep science into real-world tools that enhance resilience, recovery, and emotional balance. Having pioneered closed-loop stimulation for deep sleep, we are now extending this approach to REM — exploring how precise, phase-locked cues can reshape emotional memory without disturbing sleep integrity.
The insights shared in Singapore confirm that sleep is not only restorative but also programmable, and they point toward a future where DST’s technology could support both everyday well-being and clinical care. This path is still in its early stages, but by keeping the door open from research to application, DST ensures that today’s discoveries can grow into tomorrow’s practical solutions.