Updated: Dec 20, 2018
People with dementia often have trouble sleeping, but research has been unable to reveal whether the cognitive decline comes first or the trouble sleeping. Some research has tied insomnia and sleep apnea to an increased risk of dementia. A recent study suggests that those who spend less time in deep, rapid eye movement (REM) sleep may be more likely to develop dementia than those who get quality deep sleep.
In the study, 321 adults age 60 or older who did not have dementia participated in overnight sleep studies. After an average follow-up of 12 years, 32 people developed dementia. The data shows that for each percentage reduction in the time people spent in REM was linked to a 9% increase in the risk of dementia. The study participants spent an average 20% of their sleep time in REM sleep, but the 32 people who developed dementia spent only 17% of their sleep time in REM sleep.
Researchers also examined how long it takes one to fall asleep (called sleep latency) but did not find this to be related to the risk of developing dementia.
However, the study is not conclusive. "We observe an association between sleep and dementia but cannot determine whether reduced REM causes dementia. It is unclear whether increasing REM sleep reduces dementia risk," says lead study author Matthew Pase. The study is small and would need to be confirmed with larger groups of people. “However, good quality sleep is clearly important for overall health and well-being and the emerging picture suggests that sleep and dementia may influence each other,” concludes Pase.
Good quality sleep is clearly important for overall health and well-being
“REM sleep is considered the part of the sleep cycle where our brains get rejuvenated,” Dr. Eric Larson says. “It’s considered the best part of sleep from a perspective of gaining the rest that restores well-being.”
Whether or not a lack of REM sleep increases the risk for dementia, it is becoming clear that sleep health is strongly related to brain health. It is important to talk to your doctor about sleep issues and to practice good sleep habits to promote quality sleep.