According to a study of some 52,000 Norwegian participants, both male and female, conducted by the Norwegian University of Science and Technology, consistent sleepless nights may increase oneís risk of an acute myocardial infarction (MI, or heart attack).
Lars E. Laugsand, M.D. and his colleagues found that there was a 30-45 percent higher risk of heart attack among those who struggle to get to sleep or to stay asleep.
In fact, the more numerous the symptoms of insomnia, the greater the risk according to their report in the Journal of the American Heart Association.
The researchers observed that insomnia may affect as many as one-third of the adult population. The symptoms of insomnia are pretty straightforward and recognizable.
Additional pertinent information on insomnia could be obtained in clinical risk assessment studies. The report indicated that the results would be useful in the prevention of cardiovascular disease.
The issue of insomnia could be managed simply by following good sleep hygiene recommendations. Certain pharmacological and nonpharmacological therapies might be necessary, however, to treat chronic insomnia.
Some 52,610 men and women responded to a questionnaire which was then analyzed by the researchers. The subjects resided in a single county in Norway. The incident of heart attack was then followed by means of national vital status and hospital registries in the Nord-Trndelag Health Study.
In a period consisting of 11.4 years of follow-up, there were 2,368 heart attacks recorded.
Of the study participants, 3.3 percent reported difficulties in getting to sleep on a nightly basis. In addition, 2.5 percent of the study participants reported trouble maintaining sleep, and 8.0 percent reported nonrestorative sleep more than once a week.
It was found that among those who struggled to fall asleep each night 45 percent were at increased risk of having a heart attack compared with those who had no trouble sleeping. Among those who struggled to stay asleep it was found that 30 percent were at a heightened risk of heart attack. For those reporting nonrestorative sleep, several times a week the risk of heart attack was 27 percent.
Adjustments were allowed in the study for variations in age, educational level, marital status, gender and shift workers. Other considerations included such factors as anxiety levels and depression as well as the amount of physical activity and smoking.
Sensitivity analyses excluded the first five years of follow-up treatment as well as non-hospital verified heart attacks and people with chronic somatic disorders.
It was interesting to note that when study participants on sleep medications were excluded, it strengthened the association between trouble falling asleep and risk of heart attack.
This may indicate a connection between the use of sleep medications and fewer heart attacks, possibly because the medication reduces the initial difficulty in falling asleep. Further investigation beyond the present study is needed, however, before drawing any conclusions.
Also to be considered are other potential mechanisms that are common risk factors for heart disease and insomnia including high blood pressure and increased sympathetic activation.
In the study, sleep apnea was not assessed as that link has already been connected to cardiovascular disorder.
Additionally, the evaluation of sleep quality by means of polysomnography, the absence of data duration of sleep and the inability to exclude possible uncontrolled confounding were factors affecting conclusions in the study.
Also, the researchers caution, the results did not take into account the effects and sleep habits of those living at lower latitudes, different risks of a heart attack due to location and environmental factors, or sleeping and circadian habits.