Less Sleep, Higher Dementia Risk?
People who get less REM sleep may have a higher risk of developing dementia than those who get enough deep sleep, suggests a study published in the journal of the American Academy of Neurology.
Sleep disturbances are known to play a role in dementia, but little is known about each of the five different sleep stages. REM (rapid eye movement) sleep is the fifth stage, the one in which dreaming occurs. During this stage, the eyes move rapidly back and forth, and brain activity, body temperature, pulse, and breathing increase. The first REM stage usually occurs about an hour to an hour-and-a-half into sleep and then recurs multiple times throughout the night as the cycles repeat.
For the study, researchers analyzed 12 years of sleep data for 321 people with an average age of 67 who participated in the Framingham Heart Study. During the 12-year period, 32 people were diagnosed with some form of dementia, and of those, 24 developed Alzheimer's disease. 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 didn’t develop dementia. No other stage of sleep was associated with an increased risk for dementia.