Sleeping for Nine Hours or More Each Night Is Linked to Dementia

A study in Alzheimer's & Dementia found people who slept for nine hours or more every night had deteriorated memory and language skills that signal early dementia, reports MetroUK . These problems also were found in persons who got less than six hours of nightly sleep, while seven to eight hours is still considered the ideal sleeptime. Excessive sleep has been associated with white matter hyperintensities thought to originate from decreased blood flow to the brain, and such lesions elevate the risk of cognitive decline, dementia, and stroke. The researchers studied 5,247 Hispanic participants, between 45 and 75 years old. Only 15 percent slept an average of nine hours each night, and this group saw their cognitive performance decline across the board by the end of the seven years, while their memory worsened by 13 percent and their word fluency fell by 20 percent. "We observed that prolonged periods of sleep and chronic insomnia symptoms led to declines in memory, executive function, and processing speed," said University of Miami Miller School Professor Alberto R. Ramos. "Those measures can precede the development of mild cognitive impairment and Alzheimer's disease. We may also be able to identify at-risk persons who may benefit from early intervention to prevent or reduce the risk of dementia."