It might be a good idea to invest in good-quality sleep as a young or middle-aged adult in order to benefit later-life memory, according to the study.
The association between sleep and cognitive functioning has been extensively researched, and it is becoming increasingly accepted that sleep affects learning and memory ability.
In June last year, Medical News Today reported on a study claiming sleep helps strengthen memory after learning, while most recently, a study published in the Proceedings of the National Academy of Sciences found daytime naps may help young infants remember newly learned skills and behavior.
The researchers of this latest study - including Michael Scullin, PhD, of the Department of Psychology and Neuroscience at Baylor University in Waco, TX - note that as we age, we tend to sleep less and have less "slow-wave sleep," which is known to be important for memory.
Scullin and his colleague Donald Bliwise, of the Department of Neurology at Emory University School of Medicine in Atlanta, GA, set out to see whether these age-related sleep changes affect cognitive functioning.
'Invest in sleep up front rather than trying to compensate later'
The researchers conducted a comprehensive review of more than 200 studies dating back more than half a century, which analyzed the association between sleep and cognitive functioning.
Study participants were divided into three age groups: young (ages 18-29), middle age (ages 30-60) and old (ages 60 and older).
Scullin and Bliwise assessed self-reported data on how many hours, on average, the participants sleep each night, how long it takes them to go to sleep, the frequency at which they awake during the night and how tired they feel during the day.
Results of the analysis revealed that young and middle-aged participants tend to get more sleep and better quality sleep than older adults, and this appears to benefit their cognitive functioning later in life. "We came across studies that showed that sleeping well in middle age predicted better mental functioning 28 years later," notes Scullin.
Good sleep quality among participants in their 70s, 80s and 90s, however, appeared to have little effect on their memory, according to the team.
"We interpret the literature as suggesting that maintaining good sleep quality, at least in young adulthood and middle age, promotes better cognitive functioning and serves to protect against age-related cognitive declines," say the authors.
"If sleep benefits memory and thinking in young adults but is changed in quantity and quality with age, then the question is whether improving sleep might delay - or reverse - age-related changes in memory and thinking. It's the difference between investing up front rather than trying to compensate later."
While sleeping well in older age did not appear to affect memory, Scullin notes that past research has indicated it may still promote better cardiovascular health and reduce the risk and severity of an array of other disorders.
Contrary to the results found in this study, MNT reported on a study published in the journal Neurology last month that associated poor sleep among older men with increased risk of dementia.