People that sleep more than nine hours each night consistently had twice the risk of developing dementia in 10 years compared to participants who slept for 9 hours or less, a new study has shown. The study also found those who slept longer had smaller brain volumes.
A large group of adults enrolled in the Framingham Heart Study (FHS), were asked to indicate how long they typically slept each night. Participants were then observed for 10 years to determine who developed dementia, including dementia due to Alzheimer’s disease.
Researchers from Boston University School of Medicine (BUSM) then analyzed the sleep duration data and examined the risk of developing dementia.
Long Sleep Duration
Co-corresponding author Sudha Seshadri, MD, professor of neurology at BUSM and FHS senior investigator, explained:
“Participants without a high school degree who sleep for more than 9 hours each night had six times the risk of developing dementia in 10 years as compared to participants who slept for less. These results suggest that being highly educated may protect against dementia in the presence of long sleep duration."
It is forecast that the number of Americans with Alzheimer’s disease and other dementias will grow each year as the size and proportion of the U.S. population age 65 and older continues to increase. By 2025 the number of people age 65 and older with Alzheimer’s disease is estimated to reach 7.1 million.
Co-corresponding author Matthew Pase, PhD, fellow in the department of neurology at BUSM and investigator at the FHS, added:
“Self-reported sleep duration may be a useful clinical tool to help predict persons at risk of progressing to clinical dementia within 10 years. Persons reporting long sleep time may warrant assessment and monitoring for problems with thinking and memory."
Screening for sleeping problems may aid in the early detection of cognitive impairment and dementia. The early diagnosis of dementia has many important benefits, such as providing a patient the opportunity to more activity direct their future plans and health care decisions.
According to the researchers the results suggest that excessive sleep may be a symptom rather than a cause of the brain changes that occur with dementia. Therefore, interventions to restrict sleep duration are unlikely to reduce the risk of dementia.
Andrew J. Westwood, Alexa Beiser, Nikita Jain, Jayandra J. Himali, Charles DeCarli, Sanford H. Auerbach, Matthew P. Pase, and Sudha Seshadri Prolonged sleep duration as a marker of early neurodegeneration predicting incident dementia Neurology, doi:10.1212/WNL.0000000000003732: 1526-632X