Sleep difficulties, a problem for as many as 70 million Americans, can double one's risk of heart attack or stroke, according to a study.
The study by researchers in Taiwan found that people with insomnia were twice as likely to have heart attacks or strokes than those without the sleep disorder during the trial's four-year period. The research was presented at the American Heart Association meeting in Los Angeles.
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The findings add to previous research showing not enough sleep can contribute to high blood pressure and waking too early may raise heart risks. Sleep should be part of the patient-doctor discussion during checkups, said Kristen Knutson, a sleep researcher who wasn't part of the study.
"A lot of people and many physicians don't ask about sleep," said Knutson, an assistant professor in the Department of Medicine at the University of Chicago in a telephone interview. "The first thing is to talk to their patients and also for the patients to talk to their doctors about their sleep and discussing sleep as one of the many important health behaviors like diet and exercise."
No one is certain how lack of sleep contributes to heart attacks and strokes, she said. It may be that the body's "fight or flight" system is more active with not enough sleep, which can increase heart rate and over time increase blood pressure and raise the risk for cardiovascular disease, she said.
Chronic insomnia affects about 1 in 5 adults, and is also a risk factor for depression, substance abuse and impaired waking function, according to the National Institutes of Health.
Researchers in the study looked at more than 43,000 people ages 45 or older who were part of the Taiwan National Health Insurance Research Database, including 10,871 who were diagnosed with insomnia.
They found that over four years, there were 424 heart attacks and 3,307 strokes. Those in the insomnia group were 2.3 times more likely to have a heart attack and 1.99 times more likely to have a stroke than those who didn't suffer from the sleep disorder, the authors said.
Few studies have looked at the relationship between insomnia and heart events in Asian populations, Chien-Yi Hsu, the study's lead researcher, said. Based on the results, doctors should add sleep disturbances to the list of modifiable factors that may help prevent heart disease, including high blood pressure, smoking, obesity and diet, he said.
"Doctors should pay more attention to their patient's insomnia symptoms, and consider using different methods to improve sleep, including medical, psychological or behavioral therapy, which might improve subject quality of life and reduce the risk of cardiovascular disease," said Hsu, a doctor in the Division of Cardiology at Taipei Veterans General Hospital.