Yawning gap in reality – old folk need as much sleep as young

Published on Monday 22 February 2010 22:02

THE idea that people need less sleep as they get older is "definitely a myth", an expert said yesterday.

Sleep is just as important to older people as it is to younger folk – and ideally a 75-year-old should get as much sleep as someone of 35, says psychologist Dr Sean Drummond.

Older people appear to require less sleep because not all their sleeping occurs at night, he told a US science meeting. They tend to wake up often at night, and nod off throughout the day.

Young people, on the other hand, need a long uninterrupted spell of night-time sleep for their brains to function well.

Dr Drummond studied sleep patterns and their impact on learning ability in two groups of 33 older and 29 younger individuals. The older group had an average age of 68 and the younger 27.

After a night at Dr Drummond's sleep laboratory, both sets of participants were asked to memorise a list of nouns. At the same time, activity levels in their brains were scanned using functional magnetic resonance imaging (fMRI), which monitors oxygen take-up by neurons.

The scans showed that both groups required a sufficient amount of sleep to perform the memory task properly. But only the younger volunteers needed to get their sleep in "one consolidated chunk".

Dr Drummond believes that, as we age, the circadian mechanisms that help us sleep at night and remain awake during the day break down. As a result, older people often slept less at night – but they still need a certain number of hours of sleep in total.

Speaking at the annual meeting of the American Association for the Advancement of Science, Dr Drummond said: "It's definitely a myth that older people need less sleep. The ability to sleep in one chunk overnight goes down as we age, but the amount of sleep we need to function well does not change.

"Our data suggests that older adults would benefit from continuing to get as much sleep as they did in their 30s. That's different from person to person." He added: "The more healthy an older adult is, the more they sleep like they did when they were younger."

Sleeping soundly through the night happened less and less frequently as people get older, said Dr Drummond.

"The most common characteristic of sleep as we age is that you wake up in the middle of the night," he said.

"It leads to the question: if we can give older adults the maximum quantity and quality of sleep at night, can we reverse cognitive decline?"

Dr Matthew Walker, director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley, said that

during sleep, factual memories were transferred from a short-term storage area of the brain to the equivalent of a computer's hard disc drive.

The process was akin to "dumping" e-mail information on a computer to make space for incoming messages. Dr Walker added: "It's not just important to sleep after learning; it's critical to sleep before learning.

"This seems to prepare your brain for memory formation. Sleep almost prepares the brain like a dry sponge ready to soak up that new information."