A good night’s rest not only makes you feel refreshed in the morning, it could also help to keep dementia at bay.
Scientists believe that the dreaming stage of sleep boosts connections in the brain, helping to protect it against the onset of the disease.
And so spending just 1 per cent less time in this stage, also called the rapid eye movement (REM) stage, has been linked to a 9 per cent increase in dementia risk, a study has found.
A lack of REM sleep could also be a sign of stress, which causes people to be more easily disturbed at night, something which is also linked to dementia.
Humans can experience several REM sleep cycles during the night, when the eyes move rapidly and brain activity increases.
People also experience a higher body temperature, quicker pulse and faster breathing.
Deep sleep – also called rapid eye movement sleep – could fight off dementia, according to the Boston University study
Co-author Dr Matthew Pase, of Boston University Medical School, said: ‘We have known for some time that REM sleep is reduced in persons with dementia and some people thought that lower REM was caused by dementia. Our findings are important because we show that lower REM sleep predicts the risk of dementia occurring in the future.
‘The next step will be to determine why lower REM sleep predicts a greater risk of dementia.’
For their study, the US researchers monitored the sleeping patterns of 321 participants over the age of 60. They then followed them for up to 19 years to see if they developed dementia.
In total, 32 got dementia and 24 of these had Alzheimer’s disease. They found that those who did not go on to develop dementia were in REM sleep for around 20 per cent of their sleeping time, while those who did later develop the disease were in REM sleep for only 17 per cent of the time.
The experts calculated that for every percentage point reduction in the amount of time spent in REM, participants were 9 per cent more likely to get dementia of any kind, and 8 per cent more likely to get Alzheimer’s. Disruption in other stages of sleep was not linked with an increased risk of the disease.
However, the authors of the study, published in the journal Neurology, said it did not show cause and effect – so it was not possible to confirm whether a lack of REM sleep was causing dementia or whether it was simply an early predictor of the disease.
For their study, the US researchers monitored the sleeping patterns of 321 participants over the age of 60. They then followed them for up to 19 years to see if they developed dementia. Pictured: A stock image of a man with dementia
Dr Pase said people could try to improve their overall quality of sleep in order to maximise the amount of time they spend in the REM stage.
This includes having a regular bedtime routine, sleeping in a dark and quiet room, avoiding caffeine before bed and limiting alcohol intake.
He warned that fitness monitors, such as Fitbits, did not differentiate between sleep stages so people should not rely on these to show they were getting enough REM sleep.
Earlier this year, Dr Pase and his colleagues found people who consistently sleep more than nine hours each night had double the risk of developing dementia within ten years, compared to those who slept for nine hours or less.
Higher natural levels of lithium in drinking water may prevent dementia, a study has shown.
Lithium is known to have neuroprotective effects and is a standard treatment for bipolar disorder. It occurs naturally in drinking water at levels that vary greatly from place to place.
However, the Danish experts from the University of Copenhagen warned against adding lithium to water until further research has been carried out.