MedWire News: Insomnia is associated with a moderately increased risk for acute myocardial infarction (AMI), research suggests.

Lead author of the study Lars Laugsand (Norwegian University of Science and Technology, Trondheim) told MedWire News: "Both patients and doctors should be aware of the possible association of insomnia and AMI, and patients should talk to their doctors when having sleep problems."

Laugsand and team followed-up 52,610 Norwegian adults for a first AMI over a duration of 11.4 years. At baseline, each participant completed the Nord-Trøndelag Health Study questionnaire, which comprised questions relating to three symptoms of insomnia.

After adjusting for potential confounders, participants who reported difficulty initiating sleep every night, difficulty maintaining sleep every night, or the feeling of nonrestorative sleep more than once a week had a significant 45%, 30%, and 27% increased risk for AMI, respectively, compared with people who never experienced these sleep difficulties (all p≤0.006).

Further analysis revealed a dose-dependent association between all three insomnia symptoms combined and AMI risk (p=0.003).

After excluding participants who reported using sleep medications or sedatives daily, the association between AMI risk and insomnia was strengthened.

"Evaluation of insomnia might provide additional information in clinical risk assessment that could be useful in cardiovascular prevention," write the authors in the journal Circulation.

In his comment to MedWire News, Laugsand noted that the mechanisms underlying the association between insomnia and AMI risk remain unclear.

He speculated that "insomnia might activate the sympathetic nervous system or increase the levels of inflammation in the body which can in turn increase the risk for having AMI."

However, "our study was not designed to address these mechanisms and further studies are needed to reveal the possible mechanisms behind this association," he said.

"It is a bit early to implement the findings directly in clinical practice, because this is only one study in one population… Therefore more studies in other populations to better establish the risk associated with insomnia are needed," he added.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

Free abstract