A study conducted by Monash University has revealed that even a mere 1% reduction in deep sleep each year for individuals aged 60 and above leads to a significant 27% increase in the risk of dementia. This research suggests that preserving or enhancing deep sleep, also known as slow wave sleep, in older adults could potentially help prevent dementia.
Led by Associate Professor Matthew Pase from the Monash School of Psychological Sciences and the Turner Institute for Brain and Mental Health in Melbourne, Australia, the study, published in JAMA Neurology, involved 346 participants over 60 who were part of the Framingham Heart Study.
These participants underwent two overnight sleep studies between 1995-1998 and 2001-2003, with an average of five years between the two studies. Over the subsequent 17 years, the participants were closely monitored for the development of dementia.
The research revealed a decline in deep sleep between the two studies, indicating a loss of slow wave sleep with age. Even after adjusting for various factors such as age, sex, genetic factors, and medication use, the study found that a 1% decrease in deep sleep each year was associated with a 27% increase in the risk of dementia.
Associate Professor Pase emphasised the importance of slow wave sleep in supporting the ageing brain and clearing metabolic waste, including proteins associated with Alzheimer’s disease. This research suggests that enhancing slow wave sleep may be a modifiable risk factor for dementia.
The study relied on the unique Framingham Heart Study, which provided data from repeated overnight sleep studies and continuous surveillance for dementia. It examined how slow wave sleep changes with age and its correlation with dementia risk. The study also explored the influence of genetic risk for Alzheimer’s disease and brain volumes on slow wave sleep, discovering a link between genetic risk and the decline in slow wave sleep.