Disrupted Sleep Patterns May Increase Dementia Risk, New Study Finds

A groundbreaking study published in the journal Neurology suggests that the timing and stability of your sleep patterns could be linked to an increased risk of dementia. The research provides new evidence connecting weakened circadian rhythms—the body’s internal 24-hour clock—to cognitive decline in older adults.

Each person’s circadian rhythm regulates not only sleep and wakefulness but also affects other bodily systems, according to the Cleveland Clinic. While these internal clocks are typically self-regulating, environmental factors like light exposure can disrupt them.

Researchers from the Academy of Neurology monitored over 2,000 adults with an average age of 79 for approximately 12 days. None of the participants had dementia at the beginning of the study. Using chest-worn ECG patches—devices commonly employed in clinical settings—the team tracked participants’ rest and activity patterns to measure the strength of their circadian rhythms.

“A novel aspect of our study is that we derived circadian rhythms from a chest-worn ECG patch that is commonly used clinically,” explained lead study author Wendy Wang, Ph.D., of the Peter O’Donnell Jr. School of Public Health at UT Southwestern Medical Center in Dallas.

The participants were divided into three groups based on the strength of their circadian rhythms. The results were striking: in the group with the strongest rhythms, only 31 of 728 people developed dementia during the follow-up period. By contrast, 106 of 727 people in the weakest rhythm group were diagnosed with dementia.

After adjusting for potential confounding factors such as age, blood pressure, and heart disease, the researchers concluded that people with the weakest circadian rhythms had nearly 2.5 times the risk of developing dementia compared to those with stronger internal clocks.

The timing of peak daily activity also appeared significant. Individuals whose activity peaked at 2:15 p.m. or later showed a 45% higher dementia risk compared to those whose activity peaked earlier in the day. Approximately 7% of people in the earlier peak group developed dementia, versus 10% in the later peak group.

The researchers identified what they described as a potential “U-shaped” association between sleep-wake cycle stability and dementia risk, noting that people with consistently low activity levels throughout the day may have less stable circadian rhythms.

Wang cautioned that while the findings show a clear association, they don’t establish causation. “It’s important to note that our research does not prove that irregular circadian rhythms cause dementia, only that an association was observed,” she said.

The study had some limitations, including lack of data on sleep disorders such as obstructive sleep apnea or sleep-disordered breathing, which could influence both circadian rhythms and cognitive health. The researchers acknowledged that more investigation is needed to fully understand the potential connections.

This research adds to a growing body of evidence suggesting that sleep health plays a crucial role in cognitive function and brain health. Previous studies have linked poor sleep quality and sleep disorders to increased dementia risk, but this study is among the first to specifically examine the strength and timing of circadian rhythms using clinical-grade monitoring equipment.

For those concerned about maintaining brain health, Wang recommended developing a “strong circadian rhythm that is well-aligned with the 24-hour day.” People with robust circadian rhythms typically follow regular sleep and activity schedules, even when faced with environmental or seasonal changes that might otherwise disrupt sleep patterns.

As the global population ages and dementia rates continue to rise, these findings offer potential new pathways for early intervention and prevention strategies focused on sleep regulation and circadian health.