MONDAY, Oct. 24 (HealthDay News) -- People who have trouble
getting a decent night's sleep may also face a higher risk of heart
attack, Norwegian researchers report.
The connection between insomnia and an increased risk for heart
attack isn't clear, but sleep problems might have an effect on
blood pressure or inflammation, which can both be risk factors for
a heart attack.
"As insomnia symptoms are common and fairly easy to treat, it is important that people are aware of this connection between insomnia and heart attack, and talk to their doctors if they have sleep problems," said lead researcher Dr. Lars Erik Laugsand, an internist from the Norwegian University of Science and Technology in Trondheim.
The finding remains an association, and cause-and-effect has not
been proven. Further studies are needed to confirm the findings and
to uncover the possible mechanisms behind the association, Laugsand
The report was published in the Oct. 24 online edition of
For the study, Laugsand's team collected data on almost 53,000
men and women who took part in a national health survey in 1995-97
and answered questions about their sleep habits. In addition, the
researchers identified almost 2,400 people who had a first heart
attack over the following 11 years.
The researchers found that people who had trouble falling asleep
almost every day had a 45 percent increased risk of a heart attack,
compared with those who had no problem going to sleep.
In addition, people who had trouble staying asleep had a 30
percent higher risk of a heart attack, compared with those who had
no trouble staying asleep, the authors noted. Also, people who
didn't feel refreshed after a night's sleep had a 27 percent
increased risk of a heart attack, compared with those who did, the
In their study, Laugsand's group took into account factors such
as age, sex, marital status, education level, blood pressure,
cholesterol, diabetes, weight, exercise and shift work, along with
depression and anxiety, which can also cause insomnia.
According to the researchers, 33 percent of the general
population has at least one insomnia symptom. In addition, earlier,
smaller studies have found a connection between heart disease and
insomnia as well as high blood pressure and heart attack.
There are two important limitations to the study, the
researchers noted. First, they did not take into account for
obstructive sleep apnea, the disorder known to cause disrupted
sleep due to pauses in breathing or shallow breathing during sleep.
Second, the results may not apply to Americans because daylight
hours and sleep patterns are different than those in Norway.
Dr. Gregg Fonarow, a professor of cardiology at the University
of California, Los Angeles and a spokesman for the American Heart
Association, said a number of earlier studies have investigated
whether disturbances of sleep are independently associated with a
higher risk of a heart attack.
"These prior studies have yielded mixed results, and it remains unknown if better sleep means a healthier heart," he said.
This new, population-based study found that men and women who
reported having difficulties in falling asleep, staying asleep or
having restorative sleep had a moderate increase in risk of heart
attack over the next decade, Fonarow said.
"Further research is needed to confirm these findings, explore the potential mechanisms involved, and determine if interventions that effectively treat insomnia can reduce the risk of acute myocardial infarction," he added.
One possible explanation for the findings is that all metabolic
processes in the body are governed by what are called circadian
rhythms, which vary significantly between sleep-awake cycles, said
Dr. Edward A. Fisher, The Leon H. Charney Professor of
Cardiovascular Medicine at NYU Langone Medical Center in New York
"It is known that animals with disrupted circadian rhythms develop metabolic changes that, if they occurred in people, would increase heart disease risk," Fisher said.
"Overall, independent of the exact mechanism, the association shown seems plausible, and is yet another reason to do as the authors advise -- seek professional help for better sleep," Fisher said. "Besides improving the general quality of life, it might even provide cardiovascular benefits."
For more details on heart attacks, visit the
American Heart Association.
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