Insomnia may triple the risk of developing heart failure, a large new study
from Norway suggests.
Heart problems definitely lead to sleep problems, said lead researcher Dr
Lars Laugsand, but his team tried to determine whether the reverse might also be
"Insomnia is a frequent and easily recognised, potentially manageable and
treatable condition," said Laugsand, a postdoctoral fellow in the department of
public health at the Norwegian University of Science and Technology, in
Laugsand added that the researchers found an association between insomnia and
heart failure, not that insomnia actually causes heart failure.
"We still do not know whether heart failure is really caused by insomnia, and
it is still unclear why insomnia is linked to higher heart failure risk," he
Heart failure is a chronic condition in which the heart does not pump blood
efficiently enough to meet the body's needs.
There are some indications that a biological cause might explain an
insomnia-heart failure connection, Laugsand said. "One possible mechanism could
be that insomnia activates stress responses in the body that might negatively
affect heart function," he explained.
"If our results are confirmed by others and there is a real causal
association, evaluation of insomnia symptoms might have consequences for
cardiovascular prevention," Laugsand added.
Quality of sleep
To measure the effect of insomnia on the risk of heart failure, Laugsand's
team collected data on more than 54 000 men and women who took part in a
Norwegian study on public health factors between 1995 and 1997. None of the
participants had heart failure at the start of the study.
As part of the study, researchers asked about the quality of the
participants' sleep and if they had difficulty going to sleep and staying
After 11 years of follow-up, more than 1 400 participants had developed heart
failure, Laugsand's group found. People who had multiple insomnia symptoms had a
threefold increased risk of developing heart failure, compared to people who
slept well. When depression and anxiety were accounted for, the risk was
slightly more than fourfold.
Specifically, having difficulties going to sleep and staying asleep almost
every night, and feeling tired in the morning more than once a week, were
associated with an increased risk of heart failure, compared to people who never
or rarely suffered from these symptoms.
Body's stress responses increased
These findings remained even after the researchers took age, sex, marital
status, education, shift work, blood pressure, cholesterol, diabetes, weight,
physical activity, smoking, alcohol use and previous heart attacks into
Dr Gregg Fonarow, professor of cardiology at the University of California,
Los Angeles, said,"Heart failure results in substantial [illness], mortality and
health care expenditures."
Insomnia has been associated with an increased risk for cardiovascular events
and death, and two earlier studies have suggested that insomnia may also be
associated with the risk of heart failure, he noted.
Insomnia can increase the body's inflammatory and stress responses, said
Fonarow, who's also a spokesman for the American Heart Association.
"Activation of these systems, as well as other mechanisms, may link insomnia
to an increased risk of developing heart failure and other cardiovascular
disease," he said. "However, whether preventing or treating insomnia would lower
the risk of developing heart failure requires further study."
To learn more about insomnia, visit the National