Sleeping less can increase the risk of dementia by 27 percent

Key points:

• A Monash University study revealed that a one percent decrease in deep sleep each year, for people over 60 years of age, led to a 27 percent increased risk of dementia

• Deep sleep occurs multiple times throughout the sleep period, with non-rapid eye movement being the deepest stage of sleep

• Most adults spend up to 20 percent of their night in deep sleep

Researchers at Monash University have discovered that enhancing or maintaining deep sleep, also known as slow-wave sleep, in older years could stave off dementia.

The study, led by Associate Professor Matthew Pase from the Monash School of Psychological Sciences and the Turner Institute for Brain and Mental Health in Melbourne, looked at 346 participants over the age of 60, who completed two overnight sleep studies from 1995 to 1998 and 2001 to 2003.

These participants were then carefully followed for dementia from the time of the second sleep study through to 2018. The researchers found, on average, that the amount of deep sleep declined between the two studies, indicating slow-wave sleep loss with ageing. Over the next 17 years of follow-up, there were 52 cases of dementia.

“Slow-wave sleep or deep sleep, supports the ageing brain in many ways and we know that sleep augments the clearance of metabolic waste from the brain, including facilitating the clearance of proteins that aggregate in Alzheimer’s disease,” Associate Professor Pase said.

“However, to date, we have been unsure of the role of slow-wave sleep in the development of dementia. Our findings suggest that slow-wave sleep loss may be a modifiable dementia risk factor.”

Researchers discovered that each year-on-year percentage of decrease in deep sleep was associated with a 27 percent increase in the risk of dementia.

During deep sleep your body strengthens muscles, bones, tissue and immune function — as the brain essentially prepares itself for the next day, ready to take in more information. According to the Sleep Foundation, people who nap frequently may experience less deep sleep, as part of their deep-sleep needs have already been fulfilled during the day.

“We also examined whether genetic risk for Alzheimer’s Disease or brain volumes suggestive of early neurodegeneration were associated with a reduction in slow-wave sleep,” the assoc/prof added.

“We found that a genetic risk factor for Alzheimer’s disease, but not brain volume, was associated with accelerated declines in slow wave sleep.”

This research builds upon a study published in April that discovered people who took a sleeping pill before bed experienced a drop in the levels of essential Alzheimer’s proteins — a good sign, since higher levels of such proteins track with development of the disease.

Many people eventually diagnosed with Alzheimer’s start experiencing difficulty falling and staying asleep years before cognitive problems, such as memory loss and confusion, emerge.

How many hours of sleep do you get each night and do you believe that a good night’s sleep may do more than previously thought possible? Let the team at Talking Aged Care know and subscribe to the Aged Care Guide newsletter for more informative content.