Study links a disrupted body clock with higher dementia risk

Older adults whose internal body clocks are out of sync may be at greater risk of developing dementia, according to new research published in the journal Neurology, the medical journal of the American Academy of Neurology.

The study examined the relationship between circadian rest-activity rhythms — natural 24-hour patterns that regulate sleep, wakefulness, and physical activity — and the onset of dementia in older adults who were initially dementia-free. Researchers found that individuals with weaker or more irregular daily rhythms were more likely to develop dementia during the follow-up period than those with more robust and consistent patterns.

Circadian rhythms help coordinate essential biological processes, including hormone release, metabolism, and brain function. When these rhythms are disrupted — through fragmented sleep, reduced daytime movement, or inconsistent daily schedules — the brain may be more vulnerable to long-term damage, the researchers suggest.

Monitoring daily activity

In the study, participants wore activity-monitoring devices that tracked movement across day and night, allowing researchers to assess the strength, timing, and regularity of their daily activity cycles. Those with lower daytime activity, more nighttime movement, or less predictable patterns showed a higher likelihood of developing dementia later on.

Importantly, the association remained even after accounting for other known dementia risk factors such as age, cardiovascular disease, depression, and physical inactivity, suggesting that circadian disruption itself may play an independent role.

The findings add to growing evidence that sleep and daily behavioral rhythms are closely tied to brain health. Previous research has shown that poor sleep quality and irregular sleep schedules can interfere with the brain’s ability to clear toxic proteins associated with Alzheimer’s disease and other dementias.

Conclusions

While the study does not prove that disrupted circadian rhythms cause dementia, it highlights a potentially modifiable risk factor. Researchers note that interventions aimed at strengthening daily rhythms — such as regular physical activity, consistent sleep and wake times, and increased exposure to daylight — could be explored as strategies to reduce dementia risk.

The authors emphasize that further research is needed to determine whether improving circadian rhythms can delay or prevent cognitive decline. Still, the findings underscore the importance of daily routines in healthy aging and suggest that something as simple as maintaining a regular schedule may have meaningful benefits for long-term brain health.