Deep sleep is critical for good memory performance. But when we get older, deep sleep decreases gradually. That is why many people have memory loss later in life.
Now a recent study from Northwestern University shows that gentle sound stimulation—such as the rush of a waterfall— can significantly enhance deep sleep and improve memory.
This is because sound stimulation can synchronize to the rhythm of brain waves.
In the study, 13 people 60 and older received one night of acoustic stimulation and one night of sham stimulation.
The older adults were recruited from the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern. They took a memory test at night and again the next morning.
The study used a novel sound system that increased the effectiveness of the sound stimulation in older populations.
It also used a new approach, which reads an individual’s brain waves in real time and locks in the gentle sound stimulation during a precise moment of neuron communication during deep sleep, which varies for each person.
During deep sleep, each brain wave or oscillation slows to about one per second compared to 10 oscillations per second during wakefulness.
The team developed an algorithm that delivers the sound during the rising portion of slow wave oscillations. This stimulation enhances synchronization of the neurons’ activity.
After the sound stimulation, the older participants’ slow waves increased during sleep.
The researchers found that the sound stimulation significantly enhanced deep sleep in these people and their scores on the memory tests.
In addition, the degree of slow wave sleep enhancement was related to the degree of memory improvement. This suggests slow wave sleep remains important for memory, even in old age.
The researchers suggest that this method could be a viable intervention for longer-term use in the home.
Larger studies are needed to confirm the effect of this method and then the idea is to be able to offer this for people to use at home.
The study is published in Frontiers in Human Neuroscience.
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