Just one per cent reduction in deep sleep annually for people over 60 years of age can lead to a 27% increased risk of dementia, according to a new study. The findings emphasise the importance of deep sleep to keep dementia at bay.
The study, led by researchers from Monash University, found that a decrease in slow-wave sleep, or deep sleep, can pose worrying health risks for older adults. Deep sleep enables the clearance of metabolic waste from the brain, including facilitating the clearance of proteins that aggregate in Alzheimer’s disease, the University’s press statement explained.
Previously, researchers have been unsure about the link between slow-wave sleep and dementia. This study shows that deep sleep could be a modifiable dementia risk factor.
For the study, published in JAMA Neurology, the researchers looked at 346 participants, over 60 years of age, enrolled in the Framingham Heart Study. They had completed two overnight sleep studies from 1995 to 1998 and 2001 to 2003, with an average of five years between the two studies. These participants were then followed for dementia from the time of the second sleep study through to 2018, the statement elaborated.
The findings showed that, on average, the amount of deep sleep declined between the two studies, indicating slow-wave sleep loss with ageing. Notably, over the next 17 years of follow-up, 52 cases of dementia emerged. With each percentage decrease in deep sleep annually, a 27% increase in dementia risk was observed.
“We also examined whether genetic risk for Alzheimer’s Disease or brain volumes suggestive of early neurodegeneration was associated with a reduction in slow-wave sleep. We found that a genetic risk factor for Alzheimer’s disease, but not brain volume, was associated with accelerated declines in slow-wave sleep,” lead author Matthew Pase said in the statement.
Research on dementia risks and modifiable factors associated with it have been ongoing for decades. For instance, a study, published in the journal BMC Medicine in March, showed that eating a traditional Mediterranean-type diet, which is rich in seafood, fruit, and nuts could help in reducing the risk of dementia by almost a quarter.
Such findings add to the hope that there might be factors that can help reduce the risks and stave off dementia.