A new study has shown that poor sleep quality and varying bedtimes reduce the ability to recall information from the past in older adults. The finding was particularly significant for adults of African-American descent, reports the study.
The research was published earlier this month in the journal Frontiers in Human Neuroscience. The study was titled, “Age and Race-Related Differences in Sleep Discontinuity Linked to Associative Memory Performance and Its Neural Underpinnings” and was supported by the National Science Foundation Graduate Research Fellowship.
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The team of researchers from Georgia Institute of Technology, Atlanta, explain that this was a pilot study which included 50 adults living in and around Atlanta. The findings demonstrate the importance of good quality sleep in maintaining cognitive and memory functions.
Audrey Duarte, an associate professor in Georgia Tech's School of Psychology led this study. She is the main investigator in the Memory and Aging Lab:
The night-to-night variability in the older study participants had a major impact on their performance in tests aimed at evaluating episodic memory. The association between sleep and memory has been known, but this study's novelty is showing that the connection is particularly evident for older adults and black participants, regardless of age.”
Exploring the link between sleep quality and memory
The current study is the first to explore the effects of sleep quality on memory with respect to age, race, and ethnicity. Audrey Duarte and Emily Hokett (a Ph.D. student in the School of Psychology) conducted the study, which included 81 volunteers from Atlanta.
Of all the participants, those who already had some cognitive decline were excluded from the study. The age range of the participants was in two groups – younger ones aged between 18 and 37 years and older ones aged between 56 and 76 years. Finally, 50 adults met all the selection criteria and were included in the study.
We wanted to look at lifestyle factors to see how people sleep normally, and how their sleep patterns change over time. We wanted to know how sleep affected memory performance - how well they remembered things and how well their brains functioned depending on how well they slept.”
The team provided accelerometers to the participants to measure their sleep duration and quality over a period of seven nights. These devices were worn around the wrists.
Sleep labs usually measure the quality of sleep in more detail by measuring the brain waves. However, sleep labs are often for a single night and may not provide real life data, say the researchers. The devices used in this study, which were worn by the participants at home, therefore provided more detailed information regarding sleep quality.
After the monitoring sleep patterns, the volunteers were then sent to a Georgia Tech laboratory for an electroencephalography (EEG) to measure brain wave activity during a memory test. Participants were asked to recall a pair of words shown to them earlier and it was found that most of the older adults showed better performance in their memory tests when they had slept better.
Duarte and Hokett explained that they noted that both older and younger black participants showed a marked relationship between poor sleep and poor memory functions. African-American adults, for example, slept an average of 36 minutes less than others, resulting in a 12 percent reduced performance in the memory tests.
Stress levels impact sleep quality
The researchers also measured stress levels in all the participants to see if stress could be the underlying cause of this association. Hokett said, “The main factor that correlated with poor sleep quality in black participants was race-related stress. When participants had higher values on that measure of stress, they would also have greater sleep fragmentation, on average. We found a very significant relationship here.”
There was also a wide difference in memory performance based on sleep quality among older adults.
Next, Duarte and Hokett plan to look at the effects of poor sleep patterns on Alzheimer’s disease and dementia risk among adults. Duarte said, “In understanding normative aging, lifestyle factors are a good area to target because they are potential factors we can control. It's been known for decades that important things are happening while you sleep with regard to memory consolidation and strengthening of memories. Because we knew that sleep quality typically declines in normal aging, this was a prime target for study.”
You can imagine that many people, students among them, may have variable sleep patterns based on staying up late to study and sleeping in on weekends to catch up. This data shows that may not be the greatest strategy for optimizing memory ability.”
Hokett E, Duarte A. (2019). Age and Race-Related Differences in Sleep Discontinuity Linked to Associative Memory Performance and Its Neural Underpinnings. Frontiers in Human Neuroscience. https://www.frontiersin.org/article/10.3389/fnhum.2019.00176.