Scientists have found out that the phase of slow sleep affects the development of dementia in people over 60 years old.
The risk increases even with the loss of 1% of deep sleep per year, according to a study published in JAMA Neurology, writes Science Alert.
Deep sleep is the third stage of the 90-minute human sleep cycle, which lasts approximately 20-40 minutes. This is the most peaceful stage, when brain waves and heart rate slow down and blood pressure drops. During this phase of sleep, the bones are strengthened, the immune system is strengthened, and the brain prepares to absorb information.
“Slow-wave sleep, or deep sleep, supports the aging brain in many ways, and we know that sleep improves the brain’s clearance of metabolic waste products, including facilitating the clearance of proteins that accumulate in Alzheimer’s disease.”– says neuroscientist Matthew Pase of Monash University in Australia.
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Scientists from Australia, Canada and the USA analyzed data from two studies (conducted in 1995-1998 and 2001-2003). 346 participants took part in them.
They selected participants from the last study who were already over 60 years old in 2020 and analyzed their sleep.
“We used the data to investigate how slow-wave sleep changes with aging and whether changes in the percentage of slow-wave sleep are associated with the risk of developing dementia later in life up to 17 years later.”– says Pase.
Scientists have found that the level of slow-wave sleep in them decreases starting from the age of 60. This loss peaks between the ages of 75 and 80 and then levels off.
Comparing data from the first and second studies, scientists calculated that 1% loss of slow-wave sleep per year increases the risk of developing dementia by 27%.
At the same time, this risk is greater in relation to Alzheimer’s disease – it reaches 32%.
Low REM sleep was associated with a higher risk of cardiovascular disease, taking medications that can affect sleep, and having the APOE ε4 gene, which is linked to Alzheimer’s disease.
This study suggests a link between slow sleep loss and dementia, but requires further study.
Also read: A sleepless night can probably improve mood for a few days – study