by New research published in Neurology suggests that individuals who experience disrupted sleep in their 30s and 40s may be more likely to develop memory and thinking problems in their later years. While the study does not prove a direct causal relationship, it provides evidence of an association between sleep quality and cognitive decline.
The study, conducted by researchers at the University of California, San Francisco, emphasizes the importance of understanding the connection between sleep and cognition earlier in life, particularly in relation to the risk factors for diseases like Alzheimer’s. As signs of Alzheimer’s begin to accumulate in the brain several decades before symptoms appear, investigating the role of sleep problems as a potential risk factor is crucial.
The study involved 526 participants with an average age of 40, who were followed for a duration of 11 years. Researchers analyzed the participants’ sleep duration and quality using a wrist activity monitor worn for three consecutive days on two separate occasions. On average, participants slept for six hours.
Additionally, participants maintained a sleep diary, reporting their bedtimes and wake times, and completed a sleep quality survey. The survey measured sleep quality on a scale of zero to 21, with higher scores indicating poorer sleep quality. Approximately 46% of participants reported poor sleep quality, scoring greater than five on the survey.
Throughout the study, participants also underwent a series of memory and thinking tests, allowing researchers to assess cognitive performance.
In addition to evaluating sleep quality, the study examined sleep fragmentation, which measures the frequency of short interruptions during sleep. Researchers calculated sleep fragmentation by considering the percentage of time spent in movement or lack thereof for one minute or less. On average, participants had a sleep fragmentation score of 19%.
Based on sleep fragmentation scores, participants were divided into three groups. Among the participants with the highest sleep fragmentation scores (175 people), 44 individuals showed poor cognitive performance after 10 years, compared to 10 individuals in the group with the least disrupted sleep (176 people).
After controlling for factors such as age, gender, race, and education, the study found that individuals with the most disrupted sleep had more than twice the odds of experiencing poor cognitive performance compared to those with the least disrupted sleep. However, there was no significant difference in cognitive performance between the middle group and the group with the least disrupted sleep.
The study highlights the need for further research to explore the relationship between sleep disturbances and cognition at different stages of life. Additionally, identifying critical periods in life when sleep is more strongly associated with cognition may provide opportunities for the prevention of Alzheimer’s disease and other cognitive decline disorders.
Interestingly, the study did not find an association between the amount of time spent sleeping or self-reported sleep quality and cognitive performance in middle age.
One limitation of the study was the small sample size, which prevented researchers from fully investigating potential differences in the impact of sleep disruptions on cognition based on race or gender.
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1. Source: Coherent Market Insights, Public sources, Desk research
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