Insomnia may raise the risk of a heart attack or stroke by almost a fifth, research suggests.
The study involved more than 487,000 people with an average age of 51 who had no history of stroke or heart disease.
Participants were asked if they had any of three symptoms of insomnia at least three days per week: trouble falling asleep or staying asleep; waking up too early in the morning; or trouble staying focused during the day due to poor sleep.
They were then followed for an average of about 10 years during which there were 130,032 cases of stroke, heart attack and other similar diseases.
People who had all three symptoms of insomnia were 18 per cent more likely to develop the diseases than people who did not have any symptoms, according to the findings published by the journal Neurology.
Study author Dr Liming Li, of Beijing University, said: « These results suggest that if we can target people who are having trouble sleeping with behavioural therapies, it’s possible that we could reduce the number of cases of stroke, heart attack and other diseases later down the line. »
People who had trouble falling asleep or staying asleep were nine per cent more likely to suffer a stroke or heart disease than people who did not have those problems.
And those who woke up too early and could not get back to sleep were seven per cent more likely to develop such diseases.
Those who said they had trouble staying focused during the day due to poor sleep were 13 per cent more likely to go onto suffer a heart attack or stroke than those without the symptom.
The study was observational, meaning it did not prove that insomnia caused the increased risk of stroke and heart disease, but showed a link between poor sleep and the diseases.