Sleep has well known beneficial qualities for all manner of mental and physical factors, but much of the analyses of the importance of sleep has focused on working age people.  A recent study from Georgia Tech attempts to redress the balance by exploring how sleep affects the cognitive performance of older adults.  The study found that variability in sleep time and quality had a big impact on the memory of older adults.

“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 authors explain. “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.”

Volunteers were asked to wear accelerometers on their wrists to measure both their sleep duration and quality over a seven night period.  The researchers believe that the devices provided an accurate enough measurement of both to compensate for a lack of brain wave measurement.

This was then followed up with a visit to a lab for a memory test that also measured EEG brain activity as the volunteers tried to recall word pairs that had been shown to them earlier.  Performance in this task was closely correlated with the quality of sleep they had enjoyed that week.

Race-related stress

They then delved deeper into this correlation to test whether participants were especially stressed and why, and it emerged that much of the poor quality sleep in black participants was due to 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,” the researchers explain.

It transpired that black adults were sleeping over 30 minutes less than other volunteers, with this then resulting in a 12% decline in their memory-related brain activity.

It should be said that the sample size was relatively small, and the researchers want to test their findings against a much larger sample.  This would especially enable them to explore whether other minority groups experienced similar differentials in both sleep levels and subsequent cognitive performance.  For now however, the takeaway is that regular, quality sleep is key for strong cognitive performance.

“In understanding normative aging, lifestyle factors are a good area to target because they are potentially factors we can control,” the authors say. “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.”