Association between circadian rhythm disturbances and cognitive decline in the elderly: a systematic review

Clinical Snapshot

Key Findings

• P Value: Not reported at the review level

• Effect Size: Not quantified — narrative synthesis only; no pooled effect size reported

• Primary Outcome: Association between circadian rhythm disturbances and cognitive decline (MCI development and progression to dementia/Alzheimer's disease) in adults aged ≥60 years

• Nnt Or Sensitivity: Not applicable — no meta-analytic synthesis performed; individual study effect estimates not summarised in the abstract

• Confidence Interval: Not reported

Clinical Application

Circadian rhythm assessment via actigraphy is feasible in specialist memory clinic and sleep medicine settings but is not yet standard in primary care. Sleep quality screening tools (e.g., Pittsburgh Sleep Quality Index) are readily available. Shift work history is easily obtained in clinical history-taking. Interventions targeting circadian health (light therapy, melatonin, sleep hygiene) are low-cost and low-risk but require further evidence before routine recommendation. In Australia, cognitive decline in the elderly is a major public health priority, with dementia affecting approximately 400,000 Australians. The RACGP Guidelines for Preventive Activities in General Practice and the National Dementia Action Plan both emphasise modifiable risk factor identification. Melatonin (Circadin) is TGA-approved and PBS-listed for short-term insomnia in adults aged ≥55 years, providing a potential therapeutic avenue if circadian-cognitive links are confirmed. Actigraphy is available through sleep medicine services but is not Medicare-rebated as a standalone cognitive risk assessment tool. Australian GPs should consider sleep and circadian health as part of routine cognitive health assessments, consistent with RACGP dementia risk reduction guidance, while awaiting higher-certainty evidence from prospective cohort studies and RCTs. Community-dwelling and institutionalised elderly individuals aged 60 years and older, particularly those with early cognitive complaints, MCI, or at elevated risk of dementia. Findings are most directly applicable to patients with measurable circadian disruption via actigraphy or sleep diary.

Abstract

BACKGROUND: Circadian rhythm dysregulation may contribute to sleep-wake disorders and cognitive impairment. In the elderly, circadian abnormalities have been observed in Mild Cognitive Impairment (MCI), suggesting a possible association between neurocognitive deficits and circadian dysfunctions. OBJECTIVE: To analyze the association between circadian rhythm disturbances and cognitive decline in the population aged ≥ 60 years. METHODS: This systematic review included studies evaluating the association between circadian rhythm disturbances and cognitive decline in elderly individuals aged 60 years or older, with self-reported or objectively measured sleep data and cognitive assessment via questionnaires. Studies tracking progression from MCI to Alzheimer's disease (AD) were retained, as they capture circadian changes across the MCI-to-dementia continuum. Studies that evaluated other sleep disorders and/or other conditions of cognitive impairment exclusively or that did not specify the mean age of the participants were excluded. RESULTS: Ten studies were included, totaling 5,731 participants (5,707 eligible for analysis). Circadian exposures were organized into three domains: (1) actigraphic rest-activity rhythm metrics (amplitude, robustness, interdaily stability, intradaily variability, and acrophase); (2) sleep quality and architecture parameters (efficiency, fragmentation, latency, WASO, and melatonin timing); and (3) circadian-disrupting lifestyle exposures (rotating night shift work). Across these domains, circadian dysregulation was consistently associated with a higher risk of development or progression of MCI and dementia. CONCLUSION: Circadian and sleep disturbances negatively impact cognitive health in the elderly, reinforcing the need for further research on this association and its public health implications.

References

1. 1.Lopes, L. G., Oliveira, A. S., Fingergut, C. C., Brito, G. N. E., Gonzalez, J. V. P., Donato, K. O., Cruz, M. M. E., & Salles, C. (2026). Association between circadian rhythm disturbances and cognitive decline in the elderly: a systematic review. Neurological Sciences: Official Journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology. https://doi.org/10.2147/CLEP.S37929