Sound Therapy May Improve Sleep

Summary: A new study reveals that stimulating alpha brain waves using sound may improve sleep in individuals with dementia. The technique, known as Alpha Closed-Loop Auditory Stimulation (aCLAS), can speed up or slow down alpha rhythms depending on the timing of the sound. This non-invasive approach could offer a new therapeutic avenue for sleep disturbances in dementia.

Key Facts:

• Sound stimulation can modify alpha brain waves, which are linked to memory and perception.
• aCLAS technique can speed up or slow down alpha rhythms depending on the timing of the sound.
• This approach could potentially improve sleep in individuals with dementia.

Source: University of Surrey

Using sound to stimulate certain brain waves has the potential to help those with dementia or cognitive decline sleep better, reveals a new study. Sleep disturbances are a common feature in dementia and may affect up to half of people living with the condition.

During the study, the research team from the University of Surrey and the UK Dementia Research Institute Centre for Care Research & Technology at Imperial College London, used sound stimulation to target alpha rhythms, a type of brainwave, at precise timings of the wave to investigate how the brain responds.

Alpha rhythms have been associated with memory and perception, and changes to the rhythms have been observed in those experiencing cognitive decline and dementia.

Senior author Dr Ines Violante, Senior Lecturer in Psychological Neuroscience at the University of Surrey, said:

“Alpha oscillations are a defining characteristic of our brain’s electrical activity, but we still do not fully understand their role in shaping fundamental brain functions.

“Using sound is a powerful, non-invasive approach to stimulate certain oscillations within the brain. It is important that we find ways of manipulating these oscillations to create tools for treatment applications, as we know that brain oscillations are slower in diseases, such as Alzheimer’s disease.”

In a series of experiments, researchers used an innovative brain modulation technique known as Alpha Closed-Loop Auditory Stimulation (aCLAS), in which sounds are timed to the precise phase of alpha rhythms. To monitor the effect of stimulation, measurements of electrical activity from the brain were continuously read in real-time, and when a brain wave reached a particular phase, a sound (a burst of pink noise) was played on the participant.

Researchers observed that depending on the phase at which the sound was played, the alpha rhythm became faster or slower. The effect was also dependent on where the alpha oscillations were coming from in the brain.

Dr Henry Hebron, a former doctoral student at the University of Surrey and first author of the publication, said:

 “What we have found is that alpha oscillations can be manipulated via sound when we address this rhythm on its own terms, using a closed-loop approach. Surprisingly, when we performed our aCLAS experiment as participants were falling asleep, we observed that sounds at a particular phase prevented them from reaching deeper stages of sleep (without waking them), while the same sounds at a different phase were not disruptive.

“There is a lot more to be explored regarding neural oscillations-dependent behaviours, and we believe closed-loop approaches, such as the one we implemented here, could be key.” 

According to researchers, now they have shown they are able to influence Alpha waves with sound, the next steps will be to explore if they can modify the waves in such a way that enhances cognition and sleep, which could ultimately benefit dementia patients.

Professor Derk-Jan Dijk, Director of the Surrey Sleep Research Centre and Group Leader at the UK Dementia Research Institute Centre for Care Research & Technology Centre, said: 

“There is much to be uncovered about the role of the alpha rhythm in sleep and cognition. This technique could be influential in pushing our understanding and improving sleep functions in those with dementia. We are now investigating the effects of this closed-loop auditory stimulation approach in REM sleep, where alpha rhythms are present but their role still unknown.”

The research contributes to the United Nations’ Sustainable Development Goal 3 – Good Health and Well-being.

About this auditory neuroscience and sleep research news

Author: Natasha Meredith
Source: University of Surrey
Contact: Natasha Meredith – University of Surrey
Image: The image is credited to Neuroscience News

Original Research: Open access.
“A closed-loop auditory stimulation approach selectively modulates alpha oscillations and sleep onset dynamics in humans” by Ines Violante et al. PLOS Biology

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Abstract

A closed-loop auditory stimulation approach selectively modulates alpha oscillations and sleep onset dynamics in humans

Alpha oscillations play a vital role in managing the brain’s resources, inhibiting neural activity as a function of their phase and amplitude, and are changed in many brain disorders.

Developing minimally invasive tools to modulate alpha activity and identifying the parameters that determine its response to exogenous modulators is essential for the implementation of focussed interventions.

We introduce Alpha Closed-Loop Auditory Stimulation (αCLAS) as an EEG-based method to modulate and investigate these brain rhythms in humans with specificity and selectivity, using targeted auditory stimulation.

Across a series of independent experiments, we demonstrate that αCLAS alters alpha power, frequency, and connectivity in a phase, amplitude, and topography-dependent manner.

Using single-pulse-αCLAS, we show that the effects of auditory stimuli on alpha oscillations can be explained within the theoretical framework of oscillator theory and a phase-reset mechanism.

Finally, we demonstrate the functional relevance of our approach by showing that αCLAS can interfere with sleep onset dynamics in a phase-dependent manner.