Young and middle-age individuals who get adequate sleep could have better memory and learning abilities down the road.

People who are between the ages of 70 and 90 generally do not sleep as often as younger individuals, and sleep is not as closely linked to memory. This raises an important question about how sleep influences the brain, Baylor University reported.

"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," said Michael K. Scullin, Ph.D., director of Baylor's Sleep Neuroscience and Cognition Laboratory.

"It's the difference between investing up front rather than trying to compensate later. We came across studies that showed that sleeping well in middle age predicted better mental functioning 28 years later," he continued.

Once people reach middle age they tend to take more afternoon nap, which can help improve memory as long as they do not cut back on nighttime sleep. As they grow older people also tend to have a reduction in deep sleep and dream, which are extremely important for the function of the brain.

To make their findings the researchers reviewed over 200 studies stretching as far back as 1967. The participants were categorized by age and were asked how many hours they generally slept and how long it took them to fall asleep. They were also asked how often they typically woke up during the night and how sleepy they felt during the day.

"People sometimes disparage sleep as 'lost' time," Scullin said. But even if the link between sleep and memory lessens with age, "sleeping well still is linked to better mental health, improved cardiovascular health and fewer, less severe disorders and diseases of many kinds."

The findings were published in a recent edition of the journal Psychological Science.