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MINNEAPOLIS – Sleeping through the night may be critical for adults entering middle age hoping to avoid dementia. A new study finds that middle-aged individuals experiencing disrupted sleep may face memory challenges a decade later. This discovery could be pivotal for preventing Alzheimer’s disease — the world’s most common form of dementia.

Specifically, those in their 30s and 40s who have trouble sleeping are more likely to encounter difficulties with thinking and memory in their 40s and 50s.

“Given that signs of Alzheimer’s disease start to accumulate in the brain several decades before symptoms begin, understanding the connection between sleep and cognition earlier in life is critical for understanding the role of sleep problems as a risk factor for the disease,” says study author Yue Leng, PhD, from the University of California-San Francisco. “Our findings indicate that the quality rather than the quantity of sleep matters most for cognitive health in middle age.”

Published in the journal Neurology, the medical journal of the American Academy of Neurology, the study followed 526 participants, averaging 40 years of age, over 11 years. These participants, who averaged six hours of sleep, wore a wrist activity monitor for three days, twice about a year apart, to establish average sleep patterns. They also maintained a sleep diary, recorded bedtimes and wake times, and completed a sleep quality survey.

This survey, scored from zero to 21, indicated poorer sleep quality with higher scores. Remarkably, 46 percent of participants, totaling 239 individuals, reported poor sleep with scores above five. Additionally, they underwent a series of memory and thinking tests.

“Sleep fragmentation,” a condition where sleep is frequently and briefly interrupted, ranked as the worst type of sleep disruption. Of the 175 participants with the most disrupted sleep, 44 displayed poor cognitive performance a decade later. This contrasted with only 10 out of 176 individuals with the least disrupted sleep.

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Even after adjusting for factors like age, gender, race, and education, those with highly disrupted sleep were more than twice as likely to exhibit poor cognitive performance compared to those with the fewest number of sleep disruptions. However, the team did not observe any significant differences in cognitive performance in midlife between the middle group and those with the least disrupted sleep.

The authors highlight that while the study reveals an association between sleep quality and cognitive decline, it does not establish a direct causal relationship.

“More research is needed to assess the link between sleep disturbances and cognition at different stages of life and to identify if critical life periods exist when sleep is more strongly associated with cognition,” Leng concludes in a media release. “Future studies could open up new opportunities for the prevention of Alzheimer’s disease later in life.”

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South West News Service writer Jim Leffman contributed to this report.

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