Deep sleep could be key to how well you age - study
You may have noticed when you hit your mid-30s the ability to sleep like a log starts to fade. Turns out the consequences could be much more serious than just yawning the next day.
"Sleep changes with ageing, but it doesn't just change with ageing; it can also start to explain ageing itself," says the co-author of a new review looking at the link between sleep and the body's downward spiral.
The reviewers found ageing adults may be losing their ability to have deep, restorative sleep, and older people are likely paying for lost sleep both mentally and physically.
Co-author Matthew Walker, who leads the Sleep and Neuroimaging Laboratory at the University of California, said: "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."
As the brain aged, neurons and circuits in the areas that regulated sleep slowly degraded, resulting in a decreased amount of non-REM sleep. Non-REM deep sleep played a key role in maintaining memory and cognition.
Walker said the big debate was whether older people needed less sleep or couldn't get the sleep they needed. "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 problem had "long flown under the radar". Older people rarely reported feeling sleepy or sleep-deprived but that might be because they're used to it.
Women seemed to experience far less deterioration in non-REM deep sleep than men.
Walker said sleep decline was one of the most dramatic physiological changes in ageing, yet it was rarely talked about.
"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."
The review was published in the journal, Neuron.