A new study by researchers in the United States, has found that certain stages of sleep – deep sleep and dream sleep – appear to contribute to brain health in ways that affect risk of Alzheimer’s disease.

Results of the study published in the ‘Journal of Clinical Sleep Medicine,’ show that people who get less deep sleep or dream sleep have smaller volumes in critical brain regions.

Lack of those types of sleep particularly appears to affect the inferior parietal region, which is known to undergo early changes in Alzheimer’s disease, the researchers wrote.

Alzheimer’s disease is a progressive, neurodegenerative disorder that primarily affects memory, thinking, and reasoning skills, and is the most common cause of dementia.

It’s characterized by the buildup of amyloid plaques and tau tangles in the brain, leading to the death of brain cells.

“Our findings provide preliminary evidence that reduced neuroactivity during sleep may contribute to brain atrophy, thereby potentially increasing the risk of Alzheimer’s disease,” lead researcher Gawon Cho, a postdoctoral associate at Yale School of Medicine in New Haven, Connecticut in the United States, said in a news release.