New York, Aug 25 (IANS): Older adults who get a good night's sleep with the least disturbance and are able to dream well may be at a lower risk of developing dementia later, a research has claimed.

The study showed that spending less time in REM (rapid eye movement) sleep -- which is when most of our dreaming occurs -- and taking longer to enter REM sleep can both raise the risk of dementia.

Each percentage reduction in REM sleep was associated with a nine per cent increase in the risk of all-cause dementia and an eight per cent increase in the risk of Alzheimer's disease dementia.

"Different stages of sleep may differentially affect key features of Alzheimer's disease. Our findings implicate REM sleep mechanisms as predictors of dementia," said Matthew Pase, a doctorate student at the Boston University School of Medicine (BUSM) in the US.

For the study, which appeared in the journal Neurology, the team studied 321 participants over the age of 60.

It is common for people with dementia to experience sleep disturbance. However, it is unclear if sleep disturbance occurs as a consequence of dementia or if disturbed sleep is associated with the risk of dementia in the future, the researchers said.

Previous study had revealed that people who consistently sleep more than nine hours each night had double the risk of developing dementia in 10 years as compared to participants who slept for nine hours or less.

Further research is needed to determine whether REM sleep helps protect the brain from dementia or is sensitive to early brain changes that accompany dementia, the researchers suggested.