Can excessive sleeping accelerate cognitive decline?
Turns out that too much shut-eye could have a negative impact on brain health!
According to a novel study, people older than 65 who sleep more than nine hours a night, may accelerate their risk of developing dementia compared to those who get six to eight hours.
“Since sleep duration is potentially modifiable, the relation between sleep
duration and cognitive decline might well have practical implications for the primary prevention of [dementia and cognitive] disorders,” wrote the Spanish research team, led by Julián Benito-León (University Hospital “12 de Octubre,” Madrid, Spain).
A three year study
The study involved 2,700 volunteers age 60 or older. The men and women were monitored for more than three years. At the onset of the study, each participant underwent the mini-mental state examination (MMSE), a test designed to assess dementia and analyze the changes in brain function.
In addition, the subjects answered health and lifestyle questions, and kept detailed records of the average amount of sleep they had during a 24-hour period.
It was noted that 49 percent were “normal” sleepers who snoozed for an average of six to eight hours a night, 40 percent were “long” sleepers getting nine or more hours of shut eye at night. The remaining dozed for five hours or less every day.
Findings of the study
At the close of the study, the volunteers took the MMSE test again. The study found that all the groups of sleepers exhibited a score that was lower than the original MMSE one.
However, the biggest increase in mental impairment was found among the long sleepers. They displayed nearly double the amount of decline in cognitive function over 3 years than counterparts who slept 6-8 hours.
The results persisted even after taking into account risk factors such as age, education, and smoking and drinking habits.
Though the study demonstrates that sleeping longer than normal may be an early symptom of dementia, experts concede the mechanisms underlying this association is ambiguous.
Long sleeps showed a notable MMSE reduction, but “in absolute terms, it was a modest change.” Experts feel there is need for further research to substantiate the results of the study.
“This research suggests that the length of time you sleep and cognitive health might be linked,” said Doug Brown of the Alzheimer’s Society. “But further studies are needed to understand whether sleep duration is a cause or effect of cognitive decline.”
The findings were published online recently in the Journal of Psychiatric Research.