“Pink Noise” Boosts Older Adults’ Memory & Deep Sleep
Gentle sound stimulation known as “pink noise” is defined as random noise having equal energy per octave, having more low-frequency components than “white noise”. An example of pink noise is the rush of a waterfall. This type of pink noise when synchronized to the rhythm of brain waves significantly enhanced deep sleep in older adults and improved their ability to recall words, according to a study done at Northwestern University Medicine in Chicago and published March 8th 2017 in Frontiers in Human Neuroscience.
A release from the university notes that deep sleep is critical for memory consolidation. But beginning in middle age, deep sleep decreases substantially. Scientists believe this phenomenon contributes to memory loss in aging.
The sound stimulation significantly enhanced deep sleep in participants and their scores on a memory test.
The release quotes senior author Dr. Phyllis Zee, professor of neurology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine sleep specialist, as saying, “This is an innovative, simple and safe non-medication approach that may help improve brain health. This is a potential tool for enhancing memory in older populations and attenuating normal age-related memory decline.”
In the study, 13 participants 60 and older received one night of acoustic stimulation and one night of sham stimulation. The sham stimulation procedure was identical to the acoustic one, but participants did not hear any noise during sleep. For both the sham and acoustic stimulation sessions, the individuals took a memory test at night and again the next morning. Recall ability after the sham stimulation generally improved on the morning test by a few percent. However, the average improvement was three times larger after pink-noise stimulation.
The older adults were recruited from the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern.
The degree of slow wave sleep enhancement was related to the degree of memory improvement, suggesting slow wave sleep remains important for memory, even in old age.
Although the Northwestern scientists have not yet studied the effect of repeated nights of stimulation, this method could be a viable intervention for longer-term use in the home, Zee said.
Previous research showed acoustic simulation played during deep sleep could improve memory consolidation in young people. But it has not been tested in older adults.
The new study targeted older individuals — who have much more to gain memory-wise from enhanced deep sleep — and used a novel sound system that increased the effectiveness of the sound stimulation in older populations.
The study 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.