Problems falling asleep, staying asleep and un-refreshed when waking all equal a higher risk
Dr. Lars Erik Sande Laugsan, post-doctoral fellow in the Department of Public Health, Norwegian University of Science and Technology, Trondheim, Norway, and colleagues examined the possible association between self-reported insomnia symptoms and the risk of incident heart failure in a large Norwegian cohort, according to the study’s abstract.
Insomnia is a disorder that can make it hard to fall asleep, hard to stay asleep, or both. With insomnia, you usually awaken feeling un-refreshed, which takes a toll on your ability to function during the day. Insomnia can sap not only your energy level and mood but also your health, work performance and quality of life, according to the Mayo Clinic. It has been estimated that 6% of American’s have insomnia.
For the study researchers collected data from 54,279 men and women, aged 20 to 89 years, and had participated in the Nord-Trondelag Health study (HUNT) between 1995 and 1997 and who were free from heart failure when they joined. Participants were followed for the rates of heart failure from the start of study until 2005.
According to the American Heart Association heart failure means that the heart isn't pumping as well as it should be. Your body depends on the heart's pumping action to deliver oxygen- and nutrient-rich blood to the body's cells. When the cells are nourished properly, the body can function normally. With heart failure, the weakened heart can't supply the cells with enough blood. Heart failure is a serious condition in which there is no cure but the condition can be managed.
A total of 1412 cases of heart failure occurred during a mean follow-up of 11.3 years either identified at hospitals or by the National Cause of Death Registry.
At the time of joining the study the participants had been asked if they had difficulty going to sleep and staying asleep answered with four possible choices; never, occasionally, often and almost every night. They were also asked how many times they had woke up in the morning feeling un-refreshed(non-restorative sleep) by answering with five possible choices; never, few times a year, one or two times monthly, once weekly or more than once weekly.
Researchers adjusted for factors that could influence the results such as age, sex, marital status, education, shift work, blood pressure, cholesterol, diabetes, body mass index, physical activity, smoking, alcohol, any previous heart attack, depression and anxiety.
The results revealed for those participants that had trouble falling asleep or staying asleep and staying asleep almost every night and waking un-refreshed more than once a week was linked to a higher risk for heart failure in comparison to those who never or rarely suffered these symptoms. There was a trend showing a link between the frequency of the symptoms and the increased risk, although most of these findings did not reach statistical significance.
When researchers examined the number of symptoms they had found a statically significant three-fold higher risk for heart failure among those with all three symptoms in comparison to those who had none of the symptoms. When researchers then adjusted the findings to include depression and anxiety the risk for heart failure remained significant but carried a four-fold risk.
In their conclusion the researchers write “Insomnia is associated with an increased risk of incident heart failure. If our results are confirmed by others and causation is proved, evaluation of insomnia symptoms might have consequences for cardiovascular prevention.”
Dr. Lars Laugsand commented "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. 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."
However, he does stress the study shows insomnia is linked to an increased risk of heart failure but does not show that it causes it. He remarks 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 (often referred to as sleep hygiene), and several psychological and pharmacological therapies.”
"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 researchers write “These findings may suggest 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 for by a satisfactory depth and a 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."
This study is published today in the European Heart Journal.
More information on heart failure can be viewed online at the American Heart Association website.