Scientists believe that chronic lack of sleep can lead to dementia
It has long been known that sleep is essential for humans. And now a new study has shown that a decrease in the duration of deep sleep with age may increase the risk of developing dementia.
According to a new study, the loss of slow-wave sleep with age may increase the risk of developing dementia, CNN reports.
“We found that aging was associated with a decline in the deepest stages of sleep, known as slow-wave sleep,” Matthew P. Pace, senior author of the study published Monday in JAMA Neurology, via email. Pace is an associate professor of psychology and neuroscience at Monash University in Australia.
“We then found that people with greater declines in slow-wave sleep over time had a higher risk of developing dementia over the next 17 years of follow-up,” Pace says.
Slow-wave sleep is the third stage of sleep. which is important for brain health, explains CNN. During this stage, the body removes unwanted or potentially harmful substances from the brain, including beta-amyloid protein, a hallmark of Alzheimer's disease.
This deep sleep is thought to be the brain's most restorative sleep, said Dr. Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases in Florida.
The study authors wanted to know whether a chronic decline in slow-wave sleep over time was associated with the risk of developing dementia in humans and vice versa — whether processes associated with dementia in the brain may contribute to a decrease in the duration of this type of sleep.
«The results suggest that chronic decline in slow-wave sleep, rather than individual differences at any one time point, is important in predicting the risk of developing dementia,» said Matthew Pace.
Researchers studied 346 people with an average age of 69 years who participated in the Framingham Heart Study and completed two overnight sleep studies — one from 1995 to 1998 and the second from 1998 to 2001, — during which their sleep was monitored. The US National Heart, Lung, and Blood Institute's Framingham Heart Study identifies common factors that contribute to the development of cardiovascular disease.
The authors also examined whether any changes in the amount of slow-wave sleep participants received were associated with the development of dementia within 17 years after completion of sleep studies.
By that time, 52 participants had been diagnosed with dementia. Each percentage reduction in slow-wave sleep duration per year was associated with a 27% increased risk of dementia and a 32% increased risk of Alzheimer's dementia. The rate of slow-wave sleep loss accelerated from age 60, peaked between ages 75 and 80, and then slowed.
Those who experienced worsening of this deep sleep were more likely to have cardiovascular disease or take medications , affecting sleep, and were carriers of a gene that increases the risk of developing Alzheimer's disease (APOE ε4 allele).
“This is an important study that further demonstrates the impact of sleep quality on a person's risk of cognitive decline and dementia,” Dr. Isaacson said. – It is important not only to pay attention to the total amount of sleep a person gets each night, but also to control the quality of sleep as much as possible.
This study is not the first to find such connections — in a May study, each 10% decrease in deep sleep duration was associated with an increase in damage to the tissues that form connections between brain cells.
But the latest research still doesn't prove that loss of slow-wave sleep causes dementia, the study authors say, and It's also possible that dementia-related processes in the brain may lead to loss of sleep, a process one expert has called a «vicious cycle.»
“The accumulation of beta-amyloid in the brain may influence how much we sleep, especially as we age,” says Dr. Rudolf Tanzi, director of genetics and aging research at Massachusetts General Hospital.
“As a result, «due to insufficient slow-wave sleep, less amyloid is cleared, leading to a vicious cycle of Alzheimer's pathology,» he added. – Thus, safe drugs aimed at reducing amyloid production will be important.
Pace advised people to prioritize getting good sleep. “Good quality sleep is important for many aspects of health and can also help protect the brain as we age,” he said. — People experiencing sleep problems can consult with their doctor to discuss individual solutions.
If deep sleep “does turn out to be a proven modifiable risk factor for Alzheimer's disease and dementia, then we need to give people the opportunity track your sleep more closely,” Isaacson said.
For this purpose, he recommended wearing tracking devices that can track your stay in bed, sleep time, and time spent in each sleep stage. The devices aren't perfect, the expert warned, but «they can at least provide people at risk and their doctors with real-time information on which to take action.»
Adopting a few healthy habits — another thing that tracking devices could determine the effectiveness of, — may also help protect your sleep and brain health.
“Regular exercise helps ”release" harmful, disease-causing proteins called amyloid from brain cells, and sufficient deep sleep is needed at night to "clear" amyloid debris,» advises Dr. Isaacson.
Limiting alcohol and caffeine before bed and ensuring you get seven to nine hours of sleep at the same time each night can help improve sleep quality.