Sleeping for over nine hours may be associated with dementia in older people, especially among those with less education, reports MedPage Today.

Study participants without high school degrees who slept more than 9 hours a night had six times the risk of developing dementia over the decade-long follow-up, compared with participants who slept less than 9 hours a night.

The findings suggest that longer sleep duration may be a marker of early neurodegeneration, wrote Sudha Seshadri, MD, of the Boston University School of Medicine Alzheimer’s Disease Center, and colleagues.

Another co-author, Matthew Pase, PhD, also of Boston University, told MedPage Todaythat several previously reported studies examining self-reported sleep duration and dementia risk in older populations have had mixed findings: some suggested that it is actually sleeping for shorter periods that has the association with increased dementia risk, while others found long-duration (>9 hours) sleep to be associated with the greater risk.

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