Sleep Durations May Affect Brain Health Later in Life, Study Says

Sleep habits in midlife are associated with memory in older age.

Brigham and Women’s Hospital (BWH) researchers discovered an association between midlife and later life sleeping habits with memory, in a new study published in The Journal of the American Geriatrics Society. The study suggests that extreme changes in sleep duration from middle age to older age may worsen memory function.

According to Brigham and Women’s Hospital reps, the study was the first to evaluate what associations, if any, sleep duration at midlife and later life, and sleep duration over time, affects memory. Researchers looked at data from the 15,263 participants of the Nurses’ Health Study (female nurses aged 70 or older) who were free of stroke and depression at the time of the initial assessment.

The new report, titled, “Sleep Duration In Midlife and Later Life In Relation to Cognition: The Nurses’ Health Study,” was led by Elizabeth Devore, an instructor in medicine in the Channing Division of Network Medicine at BWH. She and her team found that women who slept five or fewer hours, or nine or more hours per day, either in midlife or later life, had worse memory, equivalent to nearly two additional years of age, than those sleeping seven hours per day. Women whose sleep duration changed by greater than two hours per day over time had worse memory than women with no change in sleep duration.

“Given the importance of preserving memory into later life, it is critical to identify modifiable factors, such as sleeping habits, that may help achieve this goal,” Devore stated in a press release. “Our findings suggest that getting an ‘average’ amount of sleep, seven hours per day, may help maintain memory in later life and that clinical interventions based on sleep therapy should be examined for the prevention of cognitive impairment.”

Specifically, researchers report that:

·         Extreme sleep durations may adversely affect memory at older ages, regardless of whether they occur at mid-life or later-life.

·         Greater changes in sleep duration appear to negatively influence memory in older adults.

·         Women with sleep durations that changed by two or more hours per day from midlife to later life performed worse on memory tests than women with no change in sleep duration, equivalent to being one to two years older in age, compared to those whose sleep duration did not change during that time period.

“These findings add to our knowledge about how sleep impacts memory,” Devore said. “More research is needed to confirm these findings and explore possible mechanisms underlying these associations.”