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 apnoea or periodic limb movement disorder), they may be unknowingly contributing to the (early) development of cardiovascular disease.

Risks of Untreated Sleep Apnoea:

Apart from feeling tired during the day, sleep apnoea can have more serious effects on your health. Some of these include increasing your risk of high blood pressure and potentially increasing your risk of developing heart failure, abnormal heart rhythms (atrial fibrillation), coronary artery disease, and strokes. You can read more about the link between these conditions and sleep apnoea below.

• High Blood Pressure: The sudden drops in blood-oxygen levels that occur during sleep apnoea cause an increase in blood pressure, and strain the cardiovascular system. This is because when the airway closes and the oxygen levels drop, carbon dioxide levels increase. In response, the brain releases adrenaline-like substances into the bloodstream which increase blood pressure, thus the link between sleep apnoea and high blood pressure. About half the people with sleep apnoea also develop high blood pressure (hypertension). While high blood pressure itself increases the risk of various forms of heart disease, there is speculation that sleep apnoea also plays a more direct role in various forms of heart disease.

• Heart Failure: Sleep apnoea may increase the risk of heart failure because of the swings in blood pressure that occur during the night in response to airway closure. This, combined with a reduction in oxygen being delivered to the heart tissue, may damage heart muscle. If there is a history of heart failure, this repeated stress to the heart may make things worse.

• Abnormal Heart Rhythms (Arrhythmias): Arrhythmias occur when the electrical impulses in the heart don’t function properly, causing the heart to beat too fast, too slow, or irregularly. One of the more common types of arrhythmias thought to be associated with sleep apnoea, 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 is unclear how sleep apnoea might increase the risk of arrhythmias, but the increase in blood pressure may play a role. 

• Coronary Artery Disease: Coronary artery disease is caused by the gradual build up of fatty deposits in coronary arteries (atherosclerosis). As the deposits (plaques) slowly narrow the coronary arteries, the heart muscles receive less blood. Eventually, diminished blood flow may cause chest pain (angina) and/or shortness of breath. A complete blockage can cause a heart attack. Sleep apnoea may increase the risk of coronary artery disease because of the changes in blood pressure and oxygen levels that can occur during the night, which may make blood vessels more susceptible to damage.

• Stroke: A stroke occurs when the blood supply to a part of the 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 the blood vessels, possibly caused by blood pressure and oxygen changes from sleep apnoea, may increase the probability of a stroke. 

What to do if you suspect you have sleep apnoea

Some common symptoms of sleep apnoea include snoring, daytime sleepiness, morning headaches, irritability and shortness of breath. If you suspect you may have sleep apnoea, talk to your GP about getting a referral to see a sleep physician, or to organise a home-based sleep study. You can also take our sleep quiz.