The finding came from a new study, the largest yet to examine the association, and was published in the European Heart Journal.
Previous research suggested that insomniacs have a moderately higher risk of having a heart attack (27 to 45% greater) than people who rarely have problems sleeping.
The new investigation involved 54,279 people between the ages of 20 and 89 who were followed for an average of over 11 years.
Results showed that the participants who experienced three insomnia symptoms were over 3 times more likely to develop heart failure compared to those with no symptoms of insomnia.
Heart failure risk linked to 3 important symptomsThe risk of heart failure was associated with three critical insomnia symptoms:
- trouble falling asleep
- problem staying asleep
- 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."
More research is needed to determine a casual relationshipAlthough an association was shown between insomnia and an elevated risk of heart failure, the study did not demonstrate a cause-and-effect relationship.
"We do not know whether heart failure is really caused by insomnia," Dr Laugsand said. However, he added, if it is, it is possible to treat insomnia by strategies including following simple suggestions regarding sleeping habits, commonly known as sleep hygiene, and many psychological and pharmacological therapies.
Assessment of sleep issues may offer further details that could be used to prevent heart failure.
More studies would be necessary to determine whether or not insomnia causes the condition.
Dr Laugsand explained:
"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 largest study yet to examine the associationFor the current study, data was gathered and analyzed from males and females who registered for the Nord-Trondelag Health study (HUNT) between 1995 and 1997. All of the subjects had no history of heart failure when they joined, according to Dr Laugsand and his team.
Heart failure is a condition in which the heart is not able to pump a sufficient amount of blood throughout the body at the correct pressure. Typically, it occurs as a result of the heart muscle becoming too weak or stiff to function as it normally does.
The volunteers were observed until 2008, by which time the researchers identified a total of 1412 cases of heart failure.
At the beginning of the report, the participants were asked whether they had a hard time falling asleep and staying asleep. They were given a list of possible answers: "never", "occasionally", "often" and "almost every night".
The subjects were also asked about whether they ever woke up in the morning not feeling refreshed, known as non-restorative sleep. Their possible answers included: "never, a ew times a year", "one to two times per month", "once a week", "more than once a week".
The experts then adjusted for factors that could have an impact on the results, including:
- shift work
- marital status
- body mass index
- blood pressure
- physical activity
- history of heart attack
There was a trend suggesting an association between the prevalence of the symptoms and raised likelihood, however, the majority of these results did not reach statistical significance, the authors noted.
After controlling for most confounding variables, other than depression and anxiety, results showed a statistically significant three-fold (353%) increased probability of heart failure for people who had all three insomnia symptoms, compared to the subjects who had no symptoms.
When the findings were adjusted to include depression and anxiety, the risk was still notable, with little over a four-fold risk (425%) of heart failure.
The experts concluded:
"We found a moderate risk increase related to the individual insomnia symptoms. However, the risk among those with all the three insomnia symptoms simultaneously was particularly high even after adjustment for established cardiovascular risk factors and psychological distress.
This finding may be interpreted as suggesting that compromising some aspects of sleep may be somehow compensated for, and the net effect on cardiovascular disease may be limited. For example, having difficulty falling asleep might be compensated by sleeping deeply, as well as good continuity of sleep. However, if the initiation of sleep is poor and combined with repeated awakenings and superficial sleep, there may not be any compensatory mechanisms."
Written by Sarah Glynn