Study Links Circadian Rhythm Disruptions to Increased Dementia Risk

Circadian rhythms, the body's internal 24-hour clock, regulate sleep, wakefulness, and various bodily functions. According to the Cleveland Clinic, while these rhythms are typically stable, factors such as light exposure can disrupt them. Those with stronger circadian rhythms generally maintain consistent sleep and activity schedules, while individuals with weaker rhythms are more susceptible to disturbances.

Researchers monitored participants using chest-worn ECG patches over an average of 12 days. They categorized the subjects based on the strength of their circadian rhythms, finding that among the strongest group, 31 out of 728 participants developed dementia, whereas this figure rose to 106 out of 727 in the weakest group. Even after adjusting for factors like age, blood pressure, and heart disease, those with the weakest rhythms showed nearly 2.5 times the risk of developing dementia.

The study also identified a possible "U-shaped" association between the stability of sleep-wake cycles and dementia risk. Specifically, individuals whose activity reached its peak at 2:15 p.m. or later had a 45% greater risk of dementia compared to those whose activity peaked earlier in the day. Roughly 10% of those in the later peak group developed dementia, compared to 7% in the earlier group.

However, the researchers acknowledged limitations, including the lack of data on sleep disorders, such as obstructive sleep apnea. Lead study author Wendy Wang, Ph.D., emphasized that while the findings indicate a correlation between circadian rhythm disturbances and dementia, they do not establish causation. She recommends that individuals aim to maintain robust circadian rhythms aligned with the natural day-night cycle.