Lack of proper sleep not only makes you feel tired and restless but can trigger several chronic health issues, including diabetes, heart disease and depression. According to a study, elderly people who lack deep sleep are at higher risk of developing dementia.

Deep sleep or slow wave sleep is a stage essential for the repair and restorative functions of the body. A person typically experiences deep sleep within an hour of falling asleep, and the duration tends to decrease as the night progresses.

For people over the age of 60, getting 1% less deep sleep a year could increase the risk of dementia by 27%, according to the latest study published in Jama Network.

"Slow-wave sleep, or deep sleep, supports the aging 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," said study lead Matthew Pase, an associate professor at the Monash School of Psychological Sciences.

"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," Pase said.

Although the study has not evaluated how the loss of sleep causes dementia, researchers believe enhancing or maintaining deep sleep could potentially help the elderly delay the onset of dementia.

The researchers looked at 346 participants above the age of 60, who completed two overnight sleep studies, from 1995 to 1998 and 2001 to 2003. There was an average of five years between the two studies.

Researchers observed a decline in deep sleep between the two studies, which was normally associated with aging. The participants were followed up for dementia from the end of the second sleep study till 2018.

"Even adjusting for age, sex, cohort, genetic factors, smoking status, sleeping medication use, antidepressant use, and anxiolytic use, each percentage decrease in deep sleep each year was associated with a 27% increase in the risk of dementia," researchers said in a news release.

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