Sleep, Insomnia and Alzheimer’s disease: an integrative review

Abstract

Objective: To analyze, in the scientific literature, the evidence on the relationship between insomnia, pathophysiological sleep mechanisms, and the risk of Alzheimer's Disease. Methods: An integrative review was conducted using the PubMed, SciELO, and LILACS databases, including studies published between 2015 and 2025, selected according to pre-established inclusion and exclusion criteria, resulting in 23 articles included in the analysis. Results: The sample showed an association, and in some cases a possible causal relationship, between insomnia and Alzheimer's Disease (AD). Slow-wave sleep deprivation impairs glymphatic system function, favoring the accumulation of beta-amyloid and tau. Patients with insomnia showed a higher risk of AD (IRR=1.73) and more pronounced decline in verbal memory and executive functions, especially among APOE ε4 allele carriers. Mendelian randomization analysis suggested a causal effect of insomnia on neurodegeneration. Conclusion: It is concluded that insomnia has a bidirectional relationship with AD, representing a possible modifiable risk factor. Given the methodological heterogeneity of the included studies, caution is recommended regarding direct causality, reinforcing the importance of early screening and management of sleep disorders as a preventive strategy in neurological health.