Rest Up: Insomnia Linked to Future Heart Failure

Shelley Wood

March 06, 2013

TRØNDHEIM, Norway Insomnia symptoms in middle age are strongly associated with the subsequent development of heart failure, a large Norwegian cohort study has found [1]. The analysis, which considered over 54 000 men and women, linked insomnia symptoms and heart failure, even in subjects who had never experienced a coronary event.

While the study does not demonstrate causation, researchers led by Dr Lars E Laugsand (Norwegian University of Science and Technology, Trondheim) say their findings have important implications for patient management and, potentially, reducing progression to heart failure.

"If subsequent studies confirm our findings and if causality is better established, the observed prospective association between insomnia and HF risk could have implications for cardiovascular prevention, since insomnia is an easily recognizable and potentially manageable condition," the authors write.

Speaking with heartwire , Laugsand stressed that the findings do not have immediate implications for physicians, beyond the fact that sleep is important to good health generally.

"I think cardiologists should talk to their patients about sleep problems, but I think it's a little too early to say that anything should be implemented in the CV risk assessment," he said. "More research is clearly needed to evaluate the possible underlying mechanisms."

For example, he continued, the chronic activation of stress responses seen in insomnia could be expected to have an impact on the heart. "Patients who are stressed both at night and during the day have increased BP, increased release of stress hormones, increased heart rate, etc, and all of these factors are related to HF, so that's a potential link between the neuroendocrine system and the sympathetic nervous system. We cannot say this is the case from our study," but it's a plausible link, he said.

Community-Based Analysis

Laugsand et al reviewed baseline data relating to insomnia symptoms from the Nord-Trøndelag Health Study on the 54 279 patients enrolled between 1995 and 1997, none of whom had HF at the study outset. By 2008, 1412 patients had developed heart failure.

In a range of analyses that took into account different factors, such as age, CVD risk factors, or psychological factors, insomnia symptoms remained strongly correlated with new-onset heart failure, with more symptoms linked with higher risk. For example, subjects who reported having "difficulty initiating sleep" on "almost every night" had a 27% to 66% risk of developing heart failure (depending on the model used), compared with subjects with no insomnia symptoms. By contrast, patients who reported "difficulty initiating sleep" on a frequent basis, in addition to "difficulty maintaining sleep" and feeling that their sleep was "nonrestorative," had a risk of heart failure that ranged from two to five times higher than in subjects with no insomnia symptoms.

Women were at an increased risk of having heart failure in relation to certain insomnia risk factors and for cumulative measures of insomnia, compared with men, but Laugsand was reluctant to make much of this observation. "You cannot say from these numbers that insomnia is more dangerous for women than men when it comes to having heart failure," he said. They have a higher relative risk, but that might be due to their lower baseline risk of HF."

The next step, said Laugsand, would be a trial treating patients for insomnia to see whether such a strategy could mitigate the development of heart failure.

"That would be the ultimate goal, to do a randomized controlled trial. This study is an observational study and saying anything too firm about causality is difficult," he cautioned. "But from the studies done in insomnia and other sleep problems, we know that sleep problems affect the physiology of the heart."