Numerous studies have shown that sleep helps boost memory. However, aging prevents the brain from reaping that benefit. Now, scientists are trying to decode why does that happen.
Psychologist Rebecca Spencer, who is the director of the Cognition and Action Lab in the UMass Amherst department of psychology, says one explanation could be that as people age, they sleep less and some critical stages of sleep are interrupted more frequently.
This suggests that it is not a change in the overall quantity of sleep that reduces the benefits sleep conveys on memory, but rather to the quality of specific sleep stages that makes the difference.
Spencer said that motor learning, the processes underlying learning to play tennis, golf or the piano, is boosted during stage two of non-REM sleep (nREM-2).
While older adults often sleep less than when they were young, nREM-2 is preserved and may even increase.
The downside, however, is that this stage of sleep is interrupted more in older people. Older adults are defined in the study as being 54 to 80 years old.
"When you sleep, the brain replays the 'movie' from your day and we believe this is how sleep improves memory. As we grow old, that movie might play a bit longer, but it is also interrupted more frequently," Spencer said.
She said that current research points to the need for continuity in nREM-2 sleep to generate the sleep benefit.
The researchers plan to conduct further studies to explore the broader role of sleep in the memory impairments commonly experiences by older adults.