Past research has found a link between disrupted sleep, which is common in aging, and poorer cognition. To date, researchers have already found evidence for an association between sleep and multiple health problems including depression and heart disease. Now researchers are exploring what role sleep plays in Alzheimer’s, cognitive performance, and health outcomes.
This study was cross-sectional in nature and included 4,417 (59% women) older adults with normal cognition across the United States, Canada, Australia, and Japan. Participants were 65 to 85 years of age (average age 71). The study consisted of self-reported measures of nightly sleep duration, which was then compared with demographic characteristics, amyloid beta burden (Alzheimer disease pathology), as well as objective and subjective cognitive function measures, and health outcomes. Sleep duration was grouped into three categories: short sleep duration was six hours or less, normal sleep duration was seven to eight hours, and long sleep duration was that of nine hours or more. The results of the study were that shorter sleep was associated with higher levels of beta amyloid (a protein that is created during normal brain cell activity, and one of the first detectable markers in Alzheimer’s) and reduced cognition, specifically in memory domains. Also, compared with normal sleep duration, short and long sleep durations were associated with higher body mass index and depression symptoms. Lastly, long sleep durations were associated with worse performance in memory domains.
The authors offered some evidence that both short and long duration of sleep are associated with some sort of cognitive decline, leading to the idea that there is a “sweet spot” for healthy sleep. The main takeaway is that it is important to maintain healthy sleep late in life.I In this study, people who sleep too much, as well as those who sleep too little, had associated risk for depression and other diseases.
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Winer JR., Deters KD, Kennedy G, Jin M, Goldstein-Piekarski A, Poston KL, https://pubmed.ncbi.nlm.nih.gov/34459862/ Mormino EC.Association of Short and Long Sleep Duration With Amyloid-β Burden and Cognition in Aging. JAMA Neurology. 2021;vol(issue):pp-pp.