Image of woman with insomnia.Insomniacs have an increased risk of developing heart failure, according to a new study published in the European Heart Journal.

The 11-year study followed 54,279 people between the ages of 20-89 and found that those who suffered from three symptoms of insomnia were 3.5 times as likely to develop heart failure, compared to those with no insomnia symptoms.

“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,” said Lars Laugsand of the Norwegian University of Science and Technology in Trondheim, Norway. “[Patients] suffering from all three insomnia symptoms simultaneously were at considerably higher risk than those who had no symptoms or only one or two symptoms.”

Researchers collected data from 54,279 men and women enrolled in the Nord-Trondelag Health study (HUNT) between 1995 and 1997, all of whom were free from heart failure when they joined. Participants then self-reported their sleep habits, citing any difficulties going to sleep or staying asleep and how often they awoke in the morning not feeling refreshed. Researchers continued monitoring until 2008, by which time there had been a total of 1,412 cases of heart failure among participants.

After analyzing the sleep surveys for those participants who suffered heart failure, researchers found that patients with all three insomnia symptoms had a 353% increased risk of heart failure, compared to those with no symptoms, according to the study.

Notably, although the study determines a link between insomnia and increased risk of heart failure, a causal relationship has not been confirmed, according to researchers.

“We do not know whether heart failure is really caused by insomnia, but if it is, insomnia is a potentially treatable condition” using several strategies, said Laugsand. “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.”

The full study is available here.