Sleep apnoea and the cardiovascular system

rumpled bedding in the morning light

At the time of writing we are in the midst of a heatwave in London, with temperatures of up to 40°C threatened over the next few days. Quite understandably a big topic of conversation at the moment is how impossible it is to sleep in such heat, and how weary everyone is feeling as a consequence.

Thankfully weather conditions like this are rare in the UK but there is a medical condition which can go undiagnosed for some time, which not only affects sleep quality and therefore how a person feels on a day to day basis, but is also associated with high blood pressure, coronary artery disease, stroke, heart failure, and the rhythm disturbance atrial fibrillation.

Sleep apnoea is a condition in which a person’s breathing stops and starts while they sleep. This generally happens as a result of the muscles in the throat relaxing too much, causing the upper airway to block. When a patient’s breathing is interrupted they wake up, but remarkably many patients do not realise they have sleep apnoea, as the wake up period is so very brief that they are not even aware of it. Often a partner will notice that there is a problem first, when their other half snores loudly, makes choking noises in their sleep, or appears to stop breathing whilst asleep.

Sleep apnoea is prognostically important, since it causes the body to release stress hormones, which promote cardiovascular disease, and it also causes rises in blood pressure and heart rate as the body struggles to meet its demands for oxygen. If it goes untreated it becomes a risk factor for liver problems, metabolic syndrome and diabetes, which in itself is a risk factor for cardiovascular disease.

If you think that you or your partner might be suffering from sleep apnoea, the first port of call should be your GP or a respiratory specialist, who will arrange what is known as a sleep study to confirm or refute the diagnosis. Treatment varies from lifestyle modification (weight loss, taking more exercise and limiting alcohol intake) to use of a CPAP (Continuous Positive Airway Pressure) machine, depending on the severity of the condition.

Drivers should also be aware that the DVLA has created a publication, which you can read here, about the dangers of driving with untreated sleep apnoea.

For a detailed breakdown of the relationship between sleep apnoea and various cardiovascular disorders, there is an excellent analysis in the Journal of the American Heart Association, which you can read here.

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