Good-quality sleep when younger, not older, may benefit later-life memory

The association between sleep and cognitive functioning has been extensively researched, and it is becoming increasingly accepted that sleep...

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 claimingsleep helps strengthen memory after learning, while most recently, a study published in the Proceedings of the National Academy of Sciencesfound 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.