Individuals with insomnia were 69% more likely to have a heart attack compared to those who didn’t have the sleep disorder during an average nine years of follow-up, according to new research presented at the recent American College of Cardiology’s Annual Scientific Session and published simultaneously in the journal Clinical Cardiology.
In addition, when looking at sleep duration as an objective measure of insomnia, researchers found that people who clocked five or fewer hours of sleep a night had the greatest risk of experiencing a heart attack, while people with both diabetes and insomnia had a twofold likelihood of having a heart attack.
The authors hope the study will help draw attention to the role that sleep disorders may play in heart health. Insomnia may include trouble falling asleep, staying asleep or getting good quality sleep. Growing in prevalence, insomnia is estimated to affect 10% to 30% of American adults, with women experiencing the disorder more than men.
“Based on our pooled data, insomnia should be considered a risk factor for developing a heart attack, and we need to do a better job of educating people about how dangerous [lack of good sleep] can be,” said study coauthor Yomna E. Dean.
For the analysis, the researchers conducted a systematic review of the literature that yielded 1,226 studies—of these, nine originating from the US, UK, Norway, Germany, Taiwan and China were selected for inclusion. The studies included data for more than a million adults (average age, 52; 43%, women); 13% of participants (153,881) had insomnia, which was defined based on ICD diagnostic codes or by the presence of any of these three symptoms: difficulty falling asleep, difficulty staying asleep or waking early and not being able to get back to sleep. Most people (96%) did not have a prior history of heart attack.
During follow-up, heart attacks occurred in 2,406 of those who had insomnia and 12,398 of those in the non-insomnia group. After controlling for other factors that could make a heart attack more likely such as age, gender, comorbidities and smoking, the analysis showed a statistically significant association between insomnia and having a heart attack.
The association remained significant across all subgroups of patients, including younger and older age (<65 and >65), follow-up duration (more or less than five years), male and female sex, and common comorbidities (diabetes, high blood pressure or cholesterol).
“Not surprisingly, people with insomnia who also had high blood pressure, cholesterol or diabetes had an even higher risk of having a heart attack than those who didn’t,” Dean said. “People with diabetes who also have insomnia had a twofold likelihood of having a heart attack.”
Moreover, people who reported five or less hours of sleep a night were 1.38 and 1.56 times more likely to experience a heart attack compared with those who slept six and seven to eight hours a night, respectively.
In a separate analysis, the researchers sought to determine whether individual insomnia symptoms are associated with a higher risk of heart attack. Disorders of initiating and maintaining sleep—that is, trouble falling or staying asleep—were also tied to a 13% increased likelihood of heart attack compared with people without these symptoms.
Based on the findings, Dean said it is important that people prioritize sleep so they get seven to eight hours of quality sleep a night.
“Practice good sleep hygiene; the room should be dark, quiet and on the cooler side, and put away devices. Do something that is calming to wind down, and if you have tried all these things and still can’t sleep or are sleeping less than five hours, talk with your doctor.”