Sleep, insomnia and Alzheimer's disease: an integrative review

OBJECTIVE: To analyze evidence in the scientific literature on the relationship between insomnia, the pathophysiological mechanisms of sleep and the risk of Alzheimer's disease. METHODS: An integrative review conducted in the PubMed, SciELO and LILACS databases, with 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 (DA). Slow-wave sleep deprivation compromises the glymphatic system, favoring the accumulation of beta-amyloid and tau. Patients with insomnia had a higher risk of DA (IRR=1.73) and a more pronounced decline in verbal memory and executive functions, especially in carriers of the APOE ε4 allele. Mendelian randomization analysis suggested a causal effect of insomnia on neurodegeneration. CONCLUSIONS: It is concluded that insomnia has a bidirectional relationship with DA, constituting a possible modifiable risk factor. Given the methodological heterogeneity of the studies, caution regarding direct causality is recommended, reinforcing the importance of screening and early management of sleep disorders as a preventive strategy in neurological health.