Getting good quality sleep and enough of it has been proven to be a nightmare for older people.
It's well known that as people age, they sleep less and wake up more frequently.
New research suggests the ageing process affects the quality of sleep people get, wreaking havoc on a person both mentally and physically and could even be implicated in the prevalence of many diseases and dementia.
A review of scientific literature published in medical journal Neuron found that adults may be losing their ability to produce deep, restorative sleep from their mid-30s.
"Sleep changes with ageing, but it doesn't just change with ageing; it can also start to explain ageing itself," said review co-author Matthew Walker, who leads the Sleep and Neuroimaging Laboratory at the University of California, Berkeley.
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"Every one of the major diseases that are killing us in first-world nations - from diabetes to obesity to Alzheimer's disease to cancer - all of those things now have strong causal links to a lack of sleep. And all of those diseases significantly increase in likelihood the older that we get, and especially in dementia."
As the brain ages, neurons and circuits in the areas that regulate sleep slowly degrade, resulting in a decreased amount of non-REM sleep.
Since non-REM deep sleep plays a key role in maintaining memory and cognition, that's a problem, says Professor Walker
There is a debate in the literature, he says, as to whether older adults need less sleep, or rather, older adults cannot generate the sleep that they need.
"The evidence seems to favour one side - older adults do not have a reduced sleep need, but instead, an impaired ability to generate sleep. The elderly therefore suffer from an unmet sleep need," said Prof Walker.
The authors stress that there is variability between individuals when it comes to sleep loss.
However the review did find that women seem to experience far less deterioration in non-REM deep sleep than men.
With loss of deep sleep starting in the mid-thirties, Prof Walker says this must been seen as an important health issue.
"We need to recognise the causal contribution of sleep disruption in the physical and mental deterioration that underlies ageing and dementia. More attention needs to be paid to the diagnosis and treatment of sleep disturbance if we are going to extend healthspan, and not just lifespan," he said.
