Sleep to beat Alzheimer's: Eight hours a night to stave off the life-shattering disease

Eight hours of quality sleep a night “banked” in formative years make people mentally sharper when they reach old age.

Even an afternoon power nap can help protect against memory decline, say researchers. While we sleep, our brains consolidate memories from the day.

Failing to get enough sleep runs the risk of memories being lost. Research team leader Professor Michael Scullin said:

“It is the difference between investing up front and trying to compensate later. “People sometimes disparage sleep as ‘lost’ time. But sleeping well is linked to better mental health, improved cardiovascular health and fewer, less severe disorders and diseases of many kinds.”

The researchers analysed more than 200 studies measuring sleep and mental functioning going back as far as 1967.

The studies classed those aged between 18 and 29 as young, those between 30 and 60 as middle aged, and the rest as old.

Participants were asked how many hours they typically slept, how long it took them to nod off, how often they woke in the middle of the night and how sleepy they felt during the day.

The research also correlated results from numerous brain wave studies and experiments dealing with sleep deprivation, napping and medications.

Professor Scullin, of Baylor University in Waco, Texas, said the results showed the benefits of a sound night’s sleep, especially for young adults, were “diverse and unmistakable”.

The study, published in the journal Perspectives On Psychological Science, is the clearest sign yet that the key to a healthy old age is nightly relaxation and recuperation.

Professor Scullin added: “We came across studies that showed sleeping well in middle age predicted better mental functioning 30 years later.”

The key to avoiding memory loss is the quality of sleep in formative years, the study found.

One particular kind of deep sleep, called “slow brainwave”, helps memory by selecting pieces of a day’s experiences, replaying them and strengthening them for better recollection.

As people grow older they tend to wake up more at night and have less deep and dream sleep, both of which are important for brain functioning.

Professor Adrian Williams of the London Sleep Centre, said: “The report is authored by respected sleep researchers and fits with our current understanding of the value of sleep in memory consolidation and protection from cardiovascular and metabolic diseases.”

His colleague Dr Irshaad Ebrahim said: “This study once again emphasises the importance of adequate sleep for total health and wellbeing.”

Family GP Ian Campbell said: “This study shows the health benefits of getting a good night’s sleep are many. Far from being ‘wasted time’, getting the right amount of sleep throughout life can clearly help reduce the risk of dementia.

“It might be due to improved brain functioning, but it might also be that those who get enough sleep are less likely to be overweight and develop high blood pressure, raised cholesterol and Type 2 diabetes, all things that make us more prone to a loss of memory in old age.”

Dr Laura Phipps of Alzheimer’s Research UK, said: “Sleep patterns can change as we get older and are often also disrupted by other health conditions including Alzheimer’s disease, making it difficult to separate cause and effect.

It’s important to understand more about the long-term benefits of sleep on brain function.”

Experts say adults should try to get between seven and eight hours sleep every night.

Some people claim to feel rested on just a few hours of sleep, but research suggests those who sleep too little over many nights do not perform as well in complex mental tasks.

Sleep is a major part of life. By the age of 85, a typical adult will have slept for nearly 250,000 hours.