Getting just the right amount of sleep — not too much, and not too little — may help prevent cognitive decline in the early stages of Alzheimer’s disease, according to a new study published in the journal Brain.
There is now a large amount of research on the connection between sleep and cognitive decline, highlighting the importance of getting enough sleep — especially if you have diabetes. One recent study found that sleeping less in middle age was linked to a greater risk of developing dementia years later. Another found that along with other healthy behaviors, sleeping 6 to 9 hours each night was linked to a lower dementia risk in people with a family history of the condition. Poor sleep may also increase the risk for dementia through its effect on diabetes — people who sleep badly have been shown to be at greater risk for type 2 diabetes, and having a longer duration of type 2 diabetes is linked to a greater risk for dementia.
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Cognitive decline linked to high or low sleep time
For the latest study, researchers at the Washington University School of Medicine in St. Louis looked at sleeping patterns over four to six nights in 100 participants. Participants were already part of a study program that involved undergoing four different types of cognitive testing, and also having genetic markers and biomarkers related to Alzheimer’s disease assessed over time. The researchers found that greater cognitive decline over time was linked to having high or low values for total sleep time, time in non-REM or REM sleep (two different sleep phases), and sleep efficiency (the amount of time in bed spent sleeping) — even after adjusting for Alzheimer’s genetic markers and biomarkers, age, sex, and education level. On the other hand, cognitive function over time was most stable in participants who feel within a middle range for total sleep time and time in both non-REM and REM sleep.
“It was particularly interesting to see that not only those with short amounts of sleep but also those with long amounts of sleep had more cognitive decline,” said study author David Holtzman, MD, a professor of neurology, in a press release on the study. “It suggests that sleep quality may be key, as opposed to simply total sleep.”
“An unanswered question is if we can intervene to improve sleep, such as increasing sleep time for short sleepers by an hour or so,” said study author Brendan Lucey, MD, an associate professor of neurology and director of the Washington University Sleep Medicine Center. “Would that have a positive effect on their cognitive performance so they no longer decline? We need more longitudinal data to answer this question” — meaning more data on both sleep patterns and cognitive performance over time.
Want to learn more about maintaining cognitive health with diabetes? Read “Nine Tips to Keep Your Memory With Diabetes,” “Keeping Your Brain Strong With Diabetes” and “Memory Fitness: How to Get It, How to Keep It.”