People with the sleep disorder insomnia may have an increased risk of developing heart failure, a new study suggests.

With insomnia, people constantly have problems falling asleep or staying asleep.

Heart failure refers to a heart that cannot meet the body's need for blood because it is not pumping properly. The main consequences of this are accumulation of fluid in the lungs or other tissues, as the blood becomes congested and cannot be pumped around the body fast enough. This accumulation of fluid may cause difficulty in breathing or swelling of the legs.

This new study involved over 54,000 people aged between 20 and 89. All were monitored for an average of 11 years. During that time, almost 1,500 cases of heart failure were recorded.

The study found that people who displayed three symptoms of insomnia had at least a three-fold increased risk of developing heart failure, compared to people who did not have insomnia.

The three symptoms of insomnia were trouble falling asleep, not being able to stay asleep and not waking up refreshed in the morning.

According to lead investigator, Dr Lars Laugsand, of the Norwegian University of Science and Technology, those suffering from all three of these symptoms ‘were at considerably higher risk than those who had no symptoms or only one or two symptoms'.

The results stood even when other factors were taken into account, such as age, gender, body mass index, cholesterol, smoking and any previous heart attack.

However, Dr Laugsand emphasised that while the study shows a link, it does not prove that insomnia causes heart failure.

"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 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.

He acknowledged that it is unclear why the conditions are linked, but one possible explanation is that insomnia ‘activates stress responses in the body that might negatively affect heart function'.

He called for further research in this area.

Details of these findings are published in the European Heart Journal.