Heart attacks happen when an artery supplying your heart with blood and oxygen becomes blocked, usually by a blood clot. The most common underlying cause of blood clots is coronary heart disease (CHD), a process whereby coronary arteries (the major blood vessels that supply the heart with blood) become clogged with deposits of cholesterol. If sleep disturbance is a common experience for you, it could be the hidden warning sign of an impending heart attack.
Sleep is essential for a person to have a healthy heart.
Those who don't sleep enough are at higher risk for cardiovascular disease and coronary heart disease—regardless of age, weight, smoking and exercise habits, say health experts.
Researchers understand that sleeping too little causes disruptions in underlying health conditions and biological processes like glucose metabolism, blood pressure, and inflammation.
In a study published in the US National Library of Medicine National Institutes of Health, sleep disturbance in women prior to myocardial infarction was investigated.
The study noted: "Myocardial Infarction (MI) is frequently unrecognized in women because they may have only vague symptoms, such as sleep disturbance.
"Describing correlates of sleep disturbance prior to MI may assist in recognizing women at risk for coronary heart disease.
"Subjective report of sleep disturbance preceding MI appears to be prevalent in women of all races and may be an important warning sign for MI in women."
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The British Heart Foundation said: "Sleep issues are particularly common among people with heart and circulatory diseases.
"In fact, as many as 44 percent of heart patients experience them.
"There can be many different reasons, ranging from breathlessness and anxiety."
A study of almost half a million people in China found that those who reported trouble getting to sleep, waking too early or not being able to function properly in the daytime had a small increased risk of having a heart attack or stroke over 10 years, compared to those without sleep problems.
The higher risk for those suffering with sleep problems ranged from roughly 10 percent for people reporting either one sleeping problem including difficulty falling or staying asleep, early rising, or not being able to function during the day, to 18 percent for those suffering with all three symptoms.
The researchers said: "Our study is the first large-scale cohort study that identified positive dose-response relationships [the more symptoms, the higher the risk] between the number of insomnia symptoms and risks of [cardiovascular disease]."
They continued: "Early detection and intervention [to treat insomnia] targeted at individual insomnia symptoms may have the potential to reduce subsequent CVD risks, especially among young adults and adults who have not developed hypertension [high blood pressure]".
One of the reasons we know how vital sleep is to the heart is that patients with sleep apnoea (which causes them to wake frequently throughout the night) often have compromised heart health, said the Sleep Foundation.
It added: "This is because without long, deep periods of rest, certain chemicals are activated that keep the body from achieving extended periods in which heart rate and blood pressure are lowered.
"Over time, this can lead to higher blood pressure during the day and a greater chance of cardiovascular problems."