People with insomnia may have a higher risk of stroke than their well-rested peers, a new study shows.
The link between insomnia and stroke was especially strong in young adults, who were up to eight times more likely to suffer a stroke if they had insomnia.
That finding - based on an analysis of health records of more than 21,000 people with insomnia and 64,000 regular sleepers in Taiwan - doesn't prove sleep disturbances cause strokes. And even among young people with insomnia, total stroke risk remained low.
"The article raises the question of, are we doctors taking chronic insomnia seriously?" Dr. Demetrius Lopes said. "It gives us ammunition to promote good sleep hygiene."
Lopes, a neurosurgeon who specializes in stroke treatment at Rush University Medical Center in Chicago, was not involved in the current study.
He said the research draws attention to the problem of stroke in young adults.
Strokes cause more serious long-term disability in the U.S. than any other disease and are the third leading cause of death, according to the National Institutes of Health. Nearly three-quarters of all strokes afflict people over the age of 65, and stroke risk more than doubles each decade after age 55.
However, some studies show that stroke incidence is rising among young adults.
For the current study, published in the journal Stroke, researchers tracked data from health insurance records, focusing on people with and without insomnia who initially had never had a stroke.
They found that over four years, 583 of the people with insomnia, or 2.7 percent, and 962 without insomnia, or 1.5 percent, were admitted to a hospital for stroke.
Although 18- to 34-year-olds were eight times more likely to have a stroke if they had been diagnosed with insomnia, their odds remained low, increasing from one out of 1,841 for people without insomnia to one out of 230 for those with insomnia.
In comparison, regular sleepers age 65 and older had a one in 24 chance of having a stroke during the study period and their peers with insomnia had a one in 15 chance of stroke.
Younger people have fewer other health conditions that might lead to stroke, allowing the relationship between insomnia and stroke to be clearer, Anna Westerlund said in an email.
Westerlund, a PhD student who has studied sleep and stroke at the Karolinska Institute in Stockholm, Sweden, was not involved in the current study.
"Older individuals have a higher overall risk of stroke due to their age and are more likely to experience conditions (that go along with) insomnia, which are also risk factors for stroke. Thus, the extent to which stroke is a consequence of insomnia is lower in older individuals than in young adults," she said.
"It is important to note that although the relative risk of stroke associated with insomnia in the young adults was very high, the public-health consequence is likely little," she added, because their overall chance of having a stroke remains low.
Nevertheless, Lopes and study author Ya-Wen Hsu stressed the value of the study in highlighting the importance of screening young adults for insomnia.
"Individuals should not simply accept insomnia as a benign, although difficult, condition that carries no major health risks," Hsu, from Chia Nan University of Pharmacy and Science at Chi-Mei Medical Center in Taiwan, said in a prepared statement. Hsu did not respond to a request for comment.
Lopes said young adults are particularly vulnerable to insomnia because they often have trouble shutting down video games and internet connections.
"Lack of sleep is an unhealthy habit. We need to work on sleep hygiene - no coffee at night, stop computer games," he said.
"This article highlights it's not okay to be up at two in the morning chronically. You've got to clean up your habits so you can avoid a chronic insomniac state," he said.
The study does not explain how insomnia and stroke may be linked. "Future research is needed to disentangle the complex of associations between insomnia and the development of stroke," the authors write.
The study also did not examine drugs prescribed to people with insomnia and whether they might contribute to stroke risk.