Sleep fails to enhance memory in older adults

Man comfortably sleeping in his bed (iStock)

Sleep may be more important for memory storage in young people than it is in older adults, a new study suggests.

In the study, young people performed better on a memory test following a night's sleep, indicating that sleep was helpful instoring their memories.

However, the same was not true for older adults, who performed about the same on the memory test regardless of whether they had slept before the test.

The findings add to a growing body of research on the role of sleep in memory storage, also known as memory consolidation. While earlier studies have suggested sleep does indeed benefit memory consolidation, nearly all of these studies have been conducted in college-age people, said study researcher Michael Scullin, a researcher at Emory University School of Medicine in Atlanta.

"We are seeing that sleep is essential to memory in younger adults. It doesn’t seem to be [as important] in older adults. That probably isn't a good thing," Scullin said.

The findings suggest that, in some way, sleep has a role in the general decline in memory seen in older adults, Scullin said.

Sleep and memory

For his study, Scullin asked 57 young adults (ages 18 to 22) and 41 older adults (ages 60 to 84) to complete a memory task. The task involved learning to associate pairs of words — for instance, if the word pair was "channel, result" participants would have to recall the word "result" when shown the word "channel."

Participants learned the words in the morning or the evening, and returned 12 hours later for a memory test.

Those who learned the words in the evening got to go home and sleep before their test. While they slept, they wore a headband device that monitored brain waves, and determined stages of sleep.

Although people in both age groups got about the same amount of total sleep, older adults got about half as much slow-wave sleep — a stage of deep sleep that has been shown to be important for memory consolidation.

Additionally, the results showed an association between the amount of slow-wave sleep and memory test scores in the younger group, but there was no such link in the older group, Scullin said.

Improving memory?

Despite the findings, the solution to improving memory in older adults might not be as simple as finding a way to increase their slow-wave sleep, Scullin said.

Scullin said it is not clear why older adults don't show the same memory benefit from sleep as young people. It could be due to changes in the brain, or the way brain areas communicate with each other, Scullin said.

Researchers need to figure out what is changing in older adults so that they can fix it, Scullin said.

"It makes sense that sleep should be linked to memory in younger adults. And we want to get that link working again in older adults," Scullin said.

Scullin presented his study here today (Aug. 2) at the American Psychology Association meeting. The work is currently being reviewed for publication.

Pass it on: Older adults do not appear to get the same memory benefit from sleep as younger people.

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