CHICAGO – A new study from Northwestern Medicine reveals that gentle sound stimulation, like the soothing sound of a waterfall, synchronized with brain wave rhythms can significantly improve deep sleep and memory recall in older adults.
Deep sleep is essential for memory consolidation, yet it tends to decline with age, which may contribute to memory loss. The research found that participants experienced enhanced deep sleep and better memory test scores when exposed to pink noise during sleep.
“This innovative and safe non-medication approach could potentially boost brain health,” said Dr. Phyllis Zee, a professor of neurology at Northwestern University Feinberg School of Medicine and a sleep specialist. “It offers a promising strategy to help improve memory and mitigate normal age-related memory decline.”
Published in Frontiers in Human Neuroscience on March 8, the study involved 13 participants aged 60 and older. Each participant underwent one night of acoustic stimulation and one night of sham stimulation, where no sound was delivered during sleep. Both sessions included memory tests conducted at night and again the following morning. While recall ability improved slightly after sham stimulation, the enhancement was three times greater following the pink-noise exposure.
The study highlighted that the increase in slow wave sleep directly correlated with memory improvement, indicating its continued importance for memory retention in older adults. Although the research has not yet examined the effects of repeated stimulation over multiple nights, Dr. Zee noted that this technique could be an effective long-term intervention for home use.
Previous studies have demonstrated that acoustic stimulation can aid memory consolidation in younger individuals, but this is the first study targeting older adults, who stand to benefit significantly from enhanced deep sleep.
The researchers employed a novel sound system that monitored participants’ brain waves in real time, delivering sound stimulation during specific moments of neuron communication during deep sleep. Each individual’s brain oscillates at a slower rate during deep sleep—about one cycle per second, compared to ten cycles per second while awake.
Giovanni Santostasi, a coauthor of the study, developed an algorithm that precisely times the sound delivery to align with the rising phase of slow wave oscillations, thereby enhancing neural synchronization. After receiving sound stimulation, participants exhibited increased slow wave activity during sleep.
Larger studies are needed to validate these findings, and the goal is to make this technology available for home use, according to Nelly Papalambros, a Ph.D. student in neuroscience and the study’s first author. “We aim to transition to long-term, at-home studies.”
Under the guidance of Dr. Roneil Malkani, Northwestern researchers are currently exploring the effects of acoustic stimulation in overnight sleep studies involving patients with memory concerns, with the aim of determining its potential to enhance memory in those with mild cognitive impairment.
Collaborative research with Ken Paller, a professor of psychology, has also indicated a link between sleep quality and memory issues in individuals with mild cognitive impairment.
The study included contributions from Northwestern researchers Sandra Weintraub and Rosemary Braun. Northwestern holds a patent pending for this technology, and Santostasi is a cofounder of DeepWave Technologies, Inc., which plans to commercialize the innovation.
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