Home' Trinidad and Tobago Guardian : June 12th 2017 Contents A24 body & soul
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Gentle sound stimulation---such as the rush of
a waterfall---synchronised to the rhythm of brain
waves significantly enhanced deep sleep in older
adults and improved their ability to recall words,
reports a new Northwestern Medicine study.
Deep sleep is critical for memory consolidation.
But beginning in middle age, deep sleep decreases
substantially, which scientists believe contributes
to memory loss in ageing.
The sound stimulation significantly enhanced deep
sleep in participants and their scores on a memory
"This is an innovative, simple and safe non-medi-
cation approach that may help improve brain health,"
said senior author Dr Phyllis Zee, professor of neu-
rology at Northwestern University Feinberg School of
Medicine and a Northwestern Medicine sleep special-
ist. "This is a potential tool for enhancing memory in
older populations and attenuating normal age-related
The study was published on March 8 in Frontiers
in Human Neuroscience.
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 ses-
sions, 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 per cent. However, the average improvement
was three times larger after pink-noise stimulation.
The older adults were recruited from the Cogni-
tive Neurology and Alzheimer's Disease Center at
The degree of slow wave sleep enhancement was
related to the degree of memory improvement, sug-
gesting slow wave sleep remains important for mem-
ory, 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
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.
During deep sleep, each brain wave or oscillation
slows to about one per second compared to ten os-
cillations per second during wakefulness.
Giovanni Santostasi, a study co-author, developed
an algorithm that delivers the sound during the rising
portion of slow wave oscillations. This stimulation
enhances synchronisation of the neurons' activity.
After the sound stimulation, the older participants'
slow waves increased during sleep.
Larger studies are needed to confirm the efficacy of
this method and then "the idea is to be able to offer
this for people to use at home," said first author Nelly
Papalambros, a PhD student in neuroscience working
in Zee's lab. "We want to move this to long-term,
Northwestern scientists, under the direction of Dr
Roneil Malkani, assistant professor of neurology at
Feinberg and a Northwestern Medicine sleep spe-
cialist, are currently testing the acoustic stimulation
in overnight sleep studies in patients with memory
complaints. The goal is to determine whether acoustic
stimulation can enhance memory in adults with mild
Previous studies conducted in individuals with mild
cognitive impairment in collaboration with Ken Paller,
professor of psychology at the Weinberg College of
Arts and Sciences at Northwestern, have demon-
strated a possible link between their sleep and their
memory impairments. (Northwestern University, USA)
Sound waves boost older
adults' memory, deep sleep
Deep sleep is critical for memory consolidation. But beginning in middle age, deep
sleep decreases substantially, which scientists believe contributes to memory
loss in ageing. PHOTO: BARANOZDEMIR
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