Brain waves can be manipulated during REM (rapid eye movement) sleep, a sleep stage linked to memory and cognition, a new study from the University of Surrey has found. New technology using sound stimulation allows scientists to speed up brain activity, which slows down in dementia patients during this phase of sleep.
In this unique study, scientists from Surrey, in collaboration with the UK Dementia Research Institute Center for Care Research and Technology at Imperial College London, used a recently developed technology, closed-loop auditory stimulation, which precisely targets brain oscillations during sleep. .
With this technology, sounds are timed to hit brain waves at certain parts (for example, the increasing and decreasing phases) of the oscillation. Sounds were delivered precisely at a rate of six (targeting theta waves) or ten (targeting alpha waves) times per second. For the first time, this was done during the REM sleep period, when brain activity is similar to being awake, but movement is inhibited.
Dr. Valeria Jaramillo, Swiss National Science Foundation Postdoctoral Fellow at the Surrey Sleep Research Center and School of Psychology, both at the University of Surrey, Emerging Leader at the UK Dementia Research Institute and first author of the publication, said:
“Brain oscillations help with the functioning of the brain and how it learns and retains information. Brain oscillations during REM sleep are involved in memory functions, but their exact role remains largely unclear. In dementia, brain activity during REM sleep slows down, which is accompanied by associated with a reduction in the ability to remember certain life events and retain information.
“Stimulating brain waves with sound can increase their frequency and this may help to better understand how brain oscillations in REM sleep promote cognition and how REM sleep can be improved in people with dementia.”
To investigate the effect of stimulation, 18 participants were recruited and monitored overnight at the Surrey Sleep Research Centre. Their sleep was continuously monitored via electrodes placed on their scalp, and the brain oscillations were analyzed in real time, so that auditory stimuli could be delivered to precise parts of the oscillations without waking the participants. Depending on which part of the cycle was targeted by the auditory stimuli, oscillations became faster or slower, showing that brain waves can be manipulated.
Professor Derk-Jan Dijk, director of the Surrey Sleep Research Center at the University of Surrey, group leader of the UK Dementia Research Institute and senior author of the publication, said:
“This could pave the way for a new approach to treating patients with dementia, as the technique is non-invasive and applied while they sleep, reducing disruption to their lives and allowing us to be more targeted in our approach.”
Using sound stimulation to alter brain oscillations while a person sleeps holds therapeutic promise. There is currently no cure for dementia, only medications that can slow the progression of the disease or temporarily relieve a person’s symptoms. So it is important that we think innovatively to develop new treatment options. Sound stimulation, a non-invasive, low-cost technique, has the potential to do exactly this.”
Dr. Ines Violante, Senior Lecturer in Psychological Neuroscience, University of Surrey and senior author of the publication
This study was published in the journal SLEEP.
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Magazine reference:
Jaramillo, V., et al. (2024) Closed-loop auditory stimulation targeting alpha and theta oscillations during REM sleep induces phase-dependent power and frequency changes. Sleep. doi.org/10.1093/sleep/zsae193.