Gentle sound stimulation, such as the rush of a waterfall, synchronized to the rhythm of brain waves significantly enhanced deep sleep in older adults and tripled their ability to recall words.
Research has shown that deep sleep plays a crucial role in memory formation. As humans age, sleep becomes lighter and more fragmentary; which in turn means that older adults get less deep sleep than younger ones. So it isn’t entirely surprising that deprivation has been linked to memory loss among the elderly.
Fortunately, there might be a rather easy fix to this problem. A new study suggests that “pink noise” can lull adults into deeper slumbers and help them form stronger memories.
“This is an innovative, simple and safe non-medication approach that may help improve brain health,” said senior author Dr. Phyllis Zee, professor of neurology at Northwestern University Feinberg School of Medicine.
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.
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 was a relatively small one, so further research is needed to confirm its findings, and study how longer-term use of pink noise effects sleep. But as first author Nelly Papalambros, a Ph.D. student in neuroscience working in Zee's lab said, Northwestern has taken steps to patent the researchers’ technology, which seems to have hit upon a way to stimulate slow waves at the right moment.
The team hopes to develop an affordable device that people can use at home, from the comfort of their beds.