Less REM Sleep Tied to Greater Risk of Dementia
People who get less rapid eye movement (REM sleep) may have a greater risk of developing dementia, according to a study published in the online issue of Neurology®, the medical journal of the American Academy of Neurology. This is the stage when dreaming occurs.
There are five stages of sleep. Stage one is light. Stage two is when the body begins to prepare for deeper sleep, including stages three and four. Stage five is REM sleep. During this dream stage, the eyes move rapidly and there is increased brain activity as well as higher body temperature, quicker pulse and faster breathing. The first REM stage occurs about an hour to an hour-and-a-half in and then recurs multiple times throughout the night as the cycles repeat.
“Sleep disturbances are common in dementia but little is known about the various stages of sleep and whether they play a role in dementia risk,” said study author Matthew P. Pase, PhD, of Swinburne University of Technology in Australia.
The people who developed dementia spent an average of 17 percent of their sleep time in REM sleep, compared to 20 percent for those who did not develop dementia. For every percent reduction in REM sleep there was a 9 percent increase in the risk of dementia. Other stages of sleep were not associated with an increased dementia risk.
“Our findings point to REM sleep as a predictor of dementia,” said Pase. “The next step will be to determine why lower REM sleep predicts a greater risk of dementia. By clarifying the role of sleep in the onset of dementia, the hope is to eventually identify possible ways to intervene so that dementia can be delayed or even prevented.”