The Link Between Sleep and Heart
It may come as a surprise to many, but medical evidence now shows that your sleep health is directly related to your heart health. This means that, whether a person is deprived of a good quantity of sleep because of work commitments, or deprived of good quality sleep because of a sleep disorder (such as sleep apnea or periodic limb movement disorder), they may be unknowingly contributing to the (early) development of cardiovascular disease.
Consider these statistics:
- A study which followed the health of over 70,000 nurses (enrolled in the Nurses Health Study) over 10 years found that those who slept for an average of 5 hours per night had a 40% increase in the risk of developing heart disease compared to those who slept for 8 hours per night. 6 hours of sleep per night translated to an increased risk of 18%.
- The Sleep Heart Health Study, the Wisconsin Sleep Cohort and other recent studies focused specifically on the effect of obstructive sleep apnea (OSA) found that OSA increases the risk of hypertension by 3-fold; stroke by 2-fold and fatal cardiovascular events by almost 3-fold.
- An estimated 50% of patients with atrial fibrillation and between 40-50% of patients with heart failure also have OSA.
- Treatment for OSA has been shown to improve nocturnal blood pressure, lower the recurrence of atrial fibrillation and reduce the risk of cardiovascular events generally.
It therefore makes sense to treat both sleep disorders and heart disease together rather than separately. An integrated approach is likely to improve quality of life.
Can My Snoring and Sleep Apnea Cause Heart Disease?
Loud snoring, the most common symptom of sleep apnea, once considered a nuisance, is now being found to be potentially a leading cause of heart problems. Apart from feeling tired during the day, sleep apnea can have more serious health effects, such as increasing your risk of high blood pressure and possibly heart failure, stroke, an abnormal heart rhythm (atrial fibrillation) and heart attacks.
What is Sleep Apnea?
Sleep apnea is a sleep disorder commonly associated with loud snoring and choking many times during sleep, and often resulting in excessive daytime sleepiness. There are 2 main types of sleep apnea:
- Obstructive Sleep Apnea: the most common, occurring when the muscles in the back of your throat relax. When the muscles relax, your airway narrows or closes as you breathe in, and breathing momentarily cuts off. This lowers the level of oxygen in your blood. Your brain senses this and briefly rouses you from sleep so that you reopen your airway. This awakening is usually so brief that you don’t remember it.
- Central Sleep Apnea: occurs when your brain fails to transmit signals to your breathing muscles. You may awaken with shortness of breath or headaches.
Sleep Apnea and the Heart
Though the potential link between sleep apnea and heart problems is an emerging field of study, the growing amount of evidence this last decade has been compelling. It is believed that sleep apnea may affect some forms of heart disease because of the drop in oxygen that occurs during sleep apnea. When your oxygen level drops, your carbon dioxide level increases. Your brain senses trouble and tells your body to release adrenaline-like substances into the bloodstream – the so-called fight-or-flight reflex – which increases blood pressure, thus the link to sleep apnea and high blood pressure.
Because of low oxygen, your body also releases other substances that can eventually damage the lining of your body’s blood vessels, and it’s this damage that might eventually cause or worsen high blood pressure and other forms of cardiovascular disease or heart problems. These include:
- High Blood Pressure: Sudden drops in blood-oxygen levels that occur during sleep apnea increase blood pressure and strain the cardiovascular system. About half the people with sleep apnea develop high blood pressure (hypertension). While high blood pressure itself increases the risk of various forms of heart disease, there’s speculation that sleep apnea also plays a more direct role in heart disease also.
- Heart Failure: Sleep apnea may increase the risk of heart failure because of the swings in blood pressure that occur during sleep apnea. This, combined with reductions in oxygen to heart tissue, might damage heart muscle. If you already have heart failure, this repeated stress to the heart might make things worse.
- Heart Rhythm Problems (Arrhythmias): Arrhythmias occur when the electrical impulses in your heart that coordinate your heartbeats don’t function properly, causing your heart to beat too fast, too slow or irregularly. One of the more common types of arrhythmias thought to be associated with sleep apnea is atrial fibrillation. This occurs when the heart’s two upper chambers (the atria) beat chaotically and irregularly – out of coordination with the two lower chambers (the ventricles) of the heart. It’s unclear how sleep apnea might increase the risk of arrhythmias, but the increase in blood pressure may play a big role.
- Coronary Artery Disease: Coronary artery disease is caused by the gradual buildup of fatty deposits in your coronary arteries (atherosclerosis). As the deposits (plaques) slowly narrow your coronary arteries, your heart muscle receives less blood. Eventually, diminished blood flow may cause chest pain (angina), shortness of breath or other symptoms. A complete blockage can cause a heart attack. Sleep apnea may increase your risk of coronary artery disease because of the swings in blood pressure that occur during sleep apnea. This, combined with dips in oxygen levels in your blood, might make your blood vessels more susceptible to damage.
- Stroke: A stroke occurs when the blood supply to a part of you brain is interrupted or severely reduced, depriving brain tissue of oxygen and nutrients. Within a few minutes, brain cells begin to die. It’s thought that damage and stress to your blood vessels, possibly caused by blood pressure and oxygen changes from sleep apnea, might make you more prone to a stroke.
Getting Help
Given that this research is an emerging field, no one can say for certain that sleep apnea will prevent heart disease. However, because it’s already known that sleep apnea can increase your risk of high blood pressure, it would only be prudent to seek treatment.