Did you know that deep sleep, also called “slow wave sleep,” plays a vital role in the healthy functioning of our brain? During this vital phase of the sleep cycle, the brain takes care of essential tasks such as eliminating metabolic waste, including proteins that are linked to Alzheimer’s.
A recent study led by Matthew Pase, an associate professor at the School of Psychological Sciences at Monash University in Australia and the Turner Institute for Brain and Mental Health in Melbourne, Australia, has found that a small reduction in the amount of sleep deepening in older adults can have serious consequences and could be considered a silent alarm of the risk of dementia. Specifically, they found that a 1% annual decrease in deep sleep in people over 60 years of age can translate into an increase in the risk of dementia of 27%.
This was the conclusion they reached after observing 346 participants with an average age of 69 years, enrolled in the Framingham Heart Study, who completed two nocturnal sleep studies in the periods from 1995 to 1998 and from 2001 to 2003, with a five-year average between the two studies. They then tracked cases of dementia in those participants back to 2018. The researchers found, on average, that the amount of deep sleep decreased between the two studies, indicating a slow loss of sleep with aging.
It is alarming to know that, during the 17 years of follow-up, 52 participants developed dementia. And the most revealing thing was that, even considering other factors such as smoking, the use of sleep medications, antidepressants and anti-anxiety medications, and genetic factors, the reduction in deep sleep remained strongly linked to the increased risk of dementia, and each percentage decrease in deep sleep each year was associated with a 27% increase in dementia risk.
The team also explored factors such as genetic risk for Alzheimer’s and brain volume as indicators of early neurodegeneration. They found that certain genetic factors, but not brain volume, were linked to an accelerated decline in deep sleep.
These results, published in JAMA Neurology, lead us to reflect on the importance of maintaining good quality sleep in the elderly and how it could be a key factor in preventing neurodegenerative diseases. Thus, improving our hours of rest, especially those of deep sleep, could be a habit not only useful for feeling rested, but also for protecting the health of our brain and helping to prevent dementia.
“Slow-wave sleep, or deep sleep, supports brain aging in many ways, and we know that sleep increases the removal of metabolic waste from the brain, including facilitating the removal of proteins that aggregate in Alzheimer’s disease. “, notes Professor Pase. “However, to date we were unsure of the role of slow wave sleep in the development of dementia. Our findings suggest that slow sleep loss may be a modifiable risk factor for dementia.” .
