6th March 2013 - The largest ever study of its kind has found people who suffer from insomnia appear to have an increased risk of developing heart failure.
The study, which is published in the European Heart Journal, followed 54,279 Norwegian people between the ages of 20-89 for an average of more than 11 years. It found that those who suffered from three symptoms of insomnia - trouble falling asleep, problems staying asleep, and not waking up feeling refreshed in the morning - had a more than three-fold increased risk of developing heart failure compared to those with no insomnia symptoms.
Researchers collected data from men and women enrolled in the Nord-Trondelag Health study between 1995 and 1997 and who were free from heart failure when they joined.
Heart failure is a condition in which the heart is unable to pump enough blood around the body at the right pressure. It usually occurs because the heart muscle has become too weak or stiff to work properly. The researchers followed the study participants until 2008, by which time there had been a total of 1,412 cases of heart failure.
After adjusting for factors that could affect the results, the researchers found that having difficulties going to sleep and staying asleep almost every night, and having non-restorative sleep more than once a week, were associated with an increased risk of heart failure when compared with people who never or rarely suffered from these symptoms.
When they looked at the number of symptoms, the researchers found a statistically significant three-fold increased risk of heart failure for people who had all three insomnia symptoms, compared to those with none, even after adjusting for most confounding factors (for example age, sex, shift work, blood pressure, diabetes, weight and smoking) apart from depression and anxiety. When they adjusted their findings to include depression and anxiety, the risk was still significant, with a slightly more than four-fold risk of heart failure.
Dr Lars Laugsand from the Norwegian University of Science and Technology, author of the report, says although the study shows that insomnia is linked to an increased risk of heart failure, it does not show that it causes it. However he told us via email: "It is possible that managing sleep problems better could reduce heart risk. However, we cannot claim that based on our own results."
Dr Laugsand says further studies are needed to investigate whether treating sleep problems would reduce the risk of heart problems. "If subsequent studies confirm our findings and if causality is better established, the observed association between insomnia and heart failure risk could have implications for cardiovascular prevention because insomnia is an easily recognized and potentially treatable condition.
"In addition to heart failure, several previous studies have investigated insomnia symptoms and risk of coronary heart disease. In these studies, including our own, the researchers generally found that insomnia was associated with an increased risk of coronary heart disease."
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