Insomnia is associated with a 26% higher risk of stroke and 28% higher odds of being admitted to hospital, according to a review published in Sleep Medicine Reviews and funded by the European Academy of Neurology. The work pulled together evidence across seven health outcomes, and stroke and hospitalization were among the clearest signals.
The review also tied insomnia to depression and suicidal behaviours, and found evidence pointing to a link with dementia, particularly Alzheimer's disease. That places chronic sleeplessness alongside more familiar cardiovascular and mental health concerns rather than treating it as a nuisance symptom that only affects the following day.
Insomnia is defined as trouble falling or staying asleep along with impaired daytime functioning, despite having adequate opportunity to sleep. It is common: an earlier meta-analysis put the prevalence of insomnia meeting international diagnostic criteria at roughly 22% of the general population, so even modest increases in risk apply to a very large number of people.
The researchers argue that insomnia deserves attention as a warning sign about the state of someone's brain and mental health, and that it should be recognized and addressed within a broader approach to reducing risk of conditions like stroke and dementia. What the review describes are associations drawn from existing evidence, so it establishes that people with insomnia carry higher risk rather than proving that treating sleep problems lowers it.