People with insomnia appear to be at increased risk of developing heart failure, according to the largest study to investigate the link. The study, published in the European Heart Journal, followed 54,279 people between the ages of 20-89 for an average of more than 11 years, and found that those who suffered from three symptoms of insomnia had a more than three-fold increased risk of developing heart failure compared to those with no insomnia symptoms.
Dr. Lars Laugsand of the Department of Public Health, Norwegian University of Science and Technology, said: “We related heart failure risk to three major insomnia symptoms including trouble falling asleep, problems staying asleep, and not waking up feeling refreshed in the morning. In our study, we found that persons suffering from insomnia have increased risk of having heart failure. Those reporting suffering from all three insomnia symptoms simultaneously were at considerably higher risk than those who had no symptoms or only one or two symptoms.”
However, he stressed that although the study shows that insomnia is linked to an increased risk of heart failure, it does not show that it causes it. “We do not know whether heart failure is really caused by insomnia, but if it is, insomnia is a potentially treatable condition using strategies such as following simple recommendations concerning sleeping habits (often referred to as sleep hygiene), and several psychological and pharmacological therapies. Evaluation of sleep problems might provide additional information that could be used in prevention of heart failure.”
He said further research would be required to establish whether or not insomnia caused the condition. “It is still unclear why insomnia is linked to higher heart failure risk. We have some indications that there might be a biological cause, and one possible explanation could be that insomnia activates stress responses in the body that might negatively affect heart function. However, further research is also needed to find the possible mechanisms for this association.”
Dr Laugsand and his colleagues collected data from men and women enrolled in the Nord-Trondelag Health study (HUNT) 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 1412 cases of heart failure.
When participants joined the study they were asked whether they had difficulty going to sleep and staying asleep, with the possible answers being “never,” “occasionally,” “often” and “almost every night.” They were also asked how often they woke up in the morning not feeling refreshed (non-restorative sleep): “never, few times a year,” “one to two times per month,” “once a week,” “more than once a week.”
The researchers found that having difficulty 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 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 (353%) increased risk of heart failure for people who had all three insomnia symptoms, compared to those with none, after adjusting for most confounding factors 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 (425%) of heart failure.
Source: Lars E. Laugsand, Linn B. Strand, Carl Platou, Lars J. Vatten, and Imre Janszky. Insomnia and the risk of incident heart failure: a population study. European Heart Journal, 2013 DOI: 10.1093/eurheartj/eht019.