Poor Sleep Quality in Early Adulthood Linked With Worse Cognitive Performance in Middle Age

Disrupted sleep in early adulthood may increase the risk of worse cognitive function at midlife, according to the authors of a study published in Neurology. In the study, participants who had the most disrupted sleep during their 30s and 40s were 2 times more likely to have worse cognitive performance during their next decade of life compared to participants who had the least disrupted sleep (after adjusting for age, gender, race, and education).

“Given that signs of Alzheimer 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,” said study author Yue Leng, PhD, assistant professor at the University of California, San Francisco, in a press release.

The study included 526 people who were assessed for sleep duration and quality (using wrist activity monitors) and sleep fragmentation, which looks at short interruptions of sleep. Participants were also tasked with keeping a sleep diary and noting their sleep and wake times, as well as completing a sleep quality survey.

The study included 526 people who were assessed for sleep duration and quality (using wrist activity monitors) and sleep fragmentation, which looks at short interruptions of sleep. Image Credit: © mast3r - stock.adobe.com

The study data showed that participants slept 6 hours on average, and nearly half of all participants (46%) reported poor sleep quality. The average sleep fragmentation was 19% (calculated by adding the percentage of time spent moving during sleep with the percentage of time there is no movement for 1 minute or less).

Investigators put people into groups based on the amount of disrupted sleep they experienced. After 11 years, researchers followed up with participants and had them perform some memory and thinking tests. The team discovered that 44 of the 175 people who were grouped as having the most disrupted sleep demonstrated poor cognitive performance. Of the 176 people who had the least amount of disrupted sleep, only 10 had poor cognitive performance.

“Our findings indicate that the quality rather than the quantity of sleep matters most for cognitive health in middle age,” said Leng in the press release.

Participants with a sleep fragmentation score that was somewhere in the middle were not significantly more likely to show cognitive decline compared to participants with the least disrupted sleep, according to the authors. However, the study authors also noted that the study was limited by small sample size, which prevented the evaluation of differences between race and gender. In addition, this study does not infer causation.

Leng said that there needs to be further research investigating the relationship between sleep disturbances and cognition throughout the various stages of life. Specifically, the authors noted that research is needed to “identify if critical life periods exist when sleep is more strongly associated with cognition.”

“Future studies could open up new opportunities for the prevention of Alzheimer’s disease later in life,” Leng said in the press release.

Reference

Even in midlife, disrupted sleep tied to memory, thinking problems later on. American Academy of Neurology. News Release. January 3, 2024. Accessed on January 4, 2024. https://www.eurekalert.org/news-releases/103008