Insomnia is more than just sleepless nights: Study finds higher stroke, dementia risk

The review, funded by the European Academy of Neurology (EAN), brings together evidence across seven health outcomes. Alongside the increased risk of stroke and hospitalisation, the researchers found that insomnia was associated with depression and suicidal behaviours, while evidence suggested a link with dementia, particularly Alzheimer’s disease.

The findings add to growing evidence that insomnia may have implications extending well beyond poor sleep and daytime functioning. Insomnia involves difficulty falling or staying asleep and impaired daytime functioning, despite adequate opportunity for sleep. A previous meta-analysis estimated that insomnia meeting international diagnostic criteria affects around 22% of the general population.

Lead author Luca Vignatelli, IRCCS Istituto delle Scienze Neurologiche di Bologna, Italy, commented, “Insomnia deserves attention as a warning sign of the status of brain and mental health. These findings show that someone with insomnia has an increased risk for dementia or stroke. Insomnia should be recognised and addressed as part of a wider approach to health to reduce the risk of developing such disorders.”

To assess the wider health impact of insomnia, the researchers searched two major medical research databases, MEDLINE and EMBASE, up to August 2025. They combined evidence from existing systematic reviews with three new systematic reviews of primary studies on stroke, occupational injuries and hospitalisation.

For stroke, nine eligible studies were identified, with six included in the meta-analysis. Overall, the systematic review included more than 1.3 million participants. The analysis found that people with insomnia had a 26% higher risk of stroke (HR 1.26; 95% CI 1.05–1.53), although the size of the association varied substantially between studies.

Five studies examined hospitalisation, three of which were included in the meta-analysis. People with insomnia had 28% higher odds of hospital admission for any reason (OR 1.28; 95% CI 1.14–1.43).

Beyond stroke and hospitalisation, the wider evidence linked insomnia with several brain and mental health outcomes. Most reviews found an association between insomnia and all-cause dementia, although findings were not consistent across all studies. Evidence was more consistent for Alzheimer’s disease, while findings for vascular dementia were mixed.

The authors note that the findings should be interpreted in light of differences in how insomnia was defined across studies and the limited consideration of sleep medication use. They also emphasise that the review identifies associations and does not establish that insomnia directly causes the conditions studied. Nevertheless, the findings support greater attention to insomnia in clinical care and the inclusion of sleep disorders and sleep hygiene in health promotion initiatives.

Study author Professor Stefan Seidel concluded, “Sleep should be part of the conversation about brain health at every age. We need to raise awareness of insomnia and its treatment, and make sure sleep is included in health promotion programmes in our communities, schools and workplaces.”