Overview
- The umbrella systematic review, published Monday, September 28, 2026, pooled data from existing reviews and new analyses covering more than 1.3 million people to assess links between insomnia and seven health outcomes.
- Meta-analysis found people with insomnia had a 26% higher risk of stroke (hazard ratio 1.26) based on six pooled studies and 28% higher odds of hospital admission for any cause (odds ratio 1.28).
- The review reported consistent associations between insomnia and Alzheimer’s disease and noted links with depression and suicidal behaviour, although results varied across different dementia subtypes and mental-health outcomes.
- Authors caution these are observational associations that do not prove cause and highlight key limits such as varied definitions of insomnia, poor reporting of sleep medication use, and study heterogeneity that weaken causal inference.
- The team and the European Academy of Neurology recommend adding sleep assessment to routine care and public-health programmes, and call for standardized diagnostic criteria and better-designed studies to clarify mechanisms and guide treatment; insomnia already affects roughly one in five people by past estimates.