For the some, the sound of a waterfall lulls them to sleep. While there's little evidence that noise machines improve sleep, there is a type of noise that does help people snooze better. A small new study found that "pink noise" enhances sleep quality, which might help prevent memory problems in older adults.
“There is a relationship between slow wave sleep and memory," said Dr. Phyllis Zee, an author of the paper in "Frontiers of Human Neuroscience" and professor of neurology at the Feinberg School of Medicine at Northwestern University. "By increasing slow wave sleep we can improve memory consolidation.”
Slow wave sleep is a stage of non-REM sleep, where people retain memories.
Pink vs white noise
Pink noise — which sounds like a swish — is similar to the more commonly-known white noise. White noise is a continuous sound that can drone out other sounds where pink noise has more low frequencies and can slow brain waves.
Previous research showed that using pink noise during slow wave sleep on young adults enhanced slow wave sleep and improved recall. But there was no evidence that it worked on older adults, who have more trouble falling asleep and grapple with memory problems more often.
So Zee and her colleagues asked 13 participants, aged 60 and older, to sleep in the lab on two days.
On both days, they took memory tests before and after sleep. During one night of sleep, participants received low bursts of pink noise when the waves rose during slow wave sleep. The other night they received a sham therapy. The morning after everyone performed better on memory tests. But they performed three times better on memory tests after they hearing pink noise.
Enhancing slow wave sleep could be a way to combat age-related memory problems.
“There is growing evidence that the decreases we see in slow wave sleep could be associated with the memory and cognitive issues associated with aging,” said Kristine Wilckens, an assistant professor of psychiatry at the University of Pittsburgh, who was not involved in the study. “This study actually enhances slow wave sleep and shows that is associated with better memory in older adults.”
While the study's technique remains experimental, people can take steps to improve their slow wave sleep. Those who use more energy during the day generally experience better slow wave sleep. Staying up longer means a person has improved slow wave sleep but that's not always advisable.
An easy way of improving it? Working out. But it can’t simply be a stroll around the block.
“It really needs to be a vigorous exercise,” Wilckens said.
There is an even easier way.
“Taking a warm bath is a good way to increase your slow wave sleep,” she said.