A review of more than 1.3 million people found an association between insomnia and a higher risk of stroke.
Researchers also found that people with insomnia were more likely to be hospitalized.
The findings show a link, but they do not prove that insomnia directly causes stroke or other health problems.
Having trouble falling asleep, staying asleep, or getting enough restful sleep can make the next day harder. But a new international review suggests that the effects of insomnia may extend beyond feeling tired or having trouble concentrating.
Researchers found an association between insomnia and several brain and mental health conditions, including stroke, dementia, depression, and suicidal behavior. The review also looked at mortality, workplace injuries, and hospital admissions.
One of the clearest findings involved stroke. The researchers found that people with insomnia had a 26% higher risk of stroke compared with people without insomnia. The review also found that people with insomnia were 28% more likely to be hospitalized for any reason.
That doesn't mean someone with insomnia is destined to have a stroke. Instead, the findings point to a relationship worth paying attention to.
Researchers pulled together existing evidence
Researchers looked at previously published systematic reviews and combined evidence from multiple studies rather than conducting one new experiment.
The researchers searched the MEDLINE and EMBASE databases, with the search extending through August 2025. They ultimately included 16 systematic reviews with meta-analyses, which examine results from multiple studies together.
Because there wasn't enough existing meta-analysis data for stroke, workplace injuries, and hospitalization, the researchers also conducted three new systematic reviews covering those areas. For the stroke analysis, they identified nine studies involving a total of 1,343,164 participants. Six of those studies were combined in a meta-analysis.
The researchers also examined evidence involving dementia, depression, suicide, and death. The results weren't equally consistent across every health outcome.
The findings don't prove insomnia causes stroke
The study's results are important, but they need to be put into context. The researchers specifically noted that the review does not prove that insomnia causes stroke.
For one thing, the studies didn't all define insomnia in exactly the same way. Other factors could also affect the results, including the use of sleep medications, which wasn't consistently accounted for across the available research.
For consumers, the takeaway isn't to panic over a few bad nights of sleep. Rather, ongoing insomnia may be worth discussing with a healthcare professional, particularly if sleep problems are persistent or interfering with daily life.
“Sleep should be part of the discussion on brain health at every stage of life,” researcher Stefan Seidel from MedUni Vienna said in a news release. “We should raise awareness of insomnia and its treatment and ensure that sleep is also taken into account in health promotion programmes in communities, schools, and the workplace.”