KUWAIT CITY, Jan 15: New research suggests that subtle changes in daily sleep–wake timing and rest–activity patterns may be an early warning sign of dementia, even in people who get sufficient sleep.

The study, published in Neurology, followed older adults from a long-running U.S. community cohort who did not have dementia at the start. Participants wore chest patches with accelerometers for about two weeks, enabling researchers to objectively measure daily rest–activity rhythms.

Results showed that participants with weaker, more irregular rhythms or later peak daily activity were more likely to be diagnosed with dementia over the following years. The findings indicate that dementia-related sleep warning signs are not about occasional sleepless nights but rather the overall consistency and strength of the body’s internal clock.

The study identified everyday experiences that may reflect these changes, including shifting sleep schedules, broken nights, increased daytime dozing, lower daytime energy, more nighttime restlessness, and a gradual drift of peak activity to later in the day.

Researchers note that the study does not prove disrupted rhythms cause dementia. However, circadian disruption may affect biological processes, including inflammation and amyloid plaque buildup, potentially contributing to neurodegeneration. Evidence also suggests that rest–activity disturbances can appear early in Alzheimer’s disease, before obvious cognitive symptoms, and worsen over time.

The authors caution against using these findings as a diagnostic tool. Observational data and unmeasured factors, such as sleep disorders like sleep apnea, may influence both circadian rhythms and dementia risk.

Despite limitations, the study adds weight to the idea that maintaining regular daily routines could support brain health. Future research will explore whether interventions that strengthen circadian rhythms, including light therapy and lifestyle adjustments, can meaningfully reduce dementia risk.