PHILADELPHIA (CBS)—A new study reveals that sleeping more than nine hours a day could double the risk of developing dementia.

Researchers at Boston University Medical Center conducted the study with the help from a large group of adults who enrolled in the Framingham Heart Study.

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The participants were asked 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 say participants without a high school degree, who slept more than 9 hours, were six times as likely to develop dementia.

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“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,” explained co-corresponding author Sudha Seshadri, MD, professor of neurology at BUSM and FHS senior investigator.

The findings also revealed those who slept longer had smaller brain volumes.

“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,” added co-corresponding author Matthew Pase, PhD, fellow in the department of neurology at BUSM and investigator at the FHS.

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The researchers believe screening for sleeping problems may aid in the early detection of cognitive impairment and dementia.