Ask The Experts

Shortened sleep duration linked to increased risk of heart disease

Q I am 54 and travel frequently for work. Recently, I have felt more tired at work and my doctor has diagnosed me with high blood pressure.

My wife says I am snoring more loudly at night. I usually get about five to six hours of sleep each night. I have read that there could be a link between a lack of sleep and heart disease. Is this true? If so, what should I do?

A The average number of hours people sleep each night has decreased by about 11/2 to two hours per night over the past 50 years. This is probably the result of people leading more hectic lives and having busier work schedules.

There is a tendency for many of us to try and cram in more and more during the day, at the expense of a good night's sleep.

However, this is detrimental to our health.

I recommend trying  to sleep more than  six hours a night  to improve your cardiovascular health and general  medical fitness.

Recent studies have shown that shortened sleep duration (fewer than six hours of sleep each night) is linked to an increased risk of cardiovascular disease, including high blood pressure, coronary artery disease and stroke.

The reason for this is unclear and may involve a number of mechanisms. These include:

• Increasing insulin resistance: This alters the way the body handles blood sugar and can increase the risk of developing diabetes.

Increasing inflammatory markers in the blood: These markers are proteins released when the body is under stress, including a lack of sleep. These proteins can cause damage to the blood vessel wall, leading to the build-up of atheroma (artery-blocking plaques) and calcium deposits in the coronary arteries and neck blood vessels.

• Reducing heart rate variability: This is a measure of the beat-to-beat variation in heart rate and of how healthy your heart is. A reduction in heart rate variability is linked to stress and increased risk of heart attack and sudden cardiac death.

Some people have a condition called sleep apnoea, in which their upper airways intermittently collapse when they sleep because the muscles that keep their airways open lose tone.

This can cause a pause (apnoeic episode) in breathing, with a sudden gasp for air after the apnoeic episode.

The person may not realise this is happening but will feel tired the next day, with reduced energy. However, his spouse may notice an increase in snoring or episodes of disordered breathing.

Sleep apnoea has been firmly linked with an increased risk of a number of cardiovascular conditions and is one of the reasons why blood pressure may be difficult to control, even with appropriate medication.

The condition can be formally diagnosed with a sleep study and should be assessed by a sleep specialist, who may recommend using a continuous positive airway pressure (CPAP) mask at night to help keep the airways open.

Losing weight is also important and, depending on the type of sleep apnoea, some patients may require surgery on their upper airways to correct the problem.

In view of the link between a lack of sleep/sleep apnoea and cardiovascular disease, a thorough cardiac assessment is recommended if you suffer from these problems, especially if you have other cardiac risk factors such as diabetes, obesity and hypertension.

I recommend trying to sleep more than six hours a night to improve your cardiovascular health and general medical fitness.

Simple measures may involve doing more physical activity during the day, developing a pre-bedtime routine such as dimming the lights and reading a book, as well as avoiding caffeine especially before bedtime, and reducing your alcohol intake.

Dr Reginald Liew

Senior consultant cardiologist at The Harley Street Heart & Cancer Centre

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A version of this article appeared in the print edition of The Straits Times on August 23, 2016, with the headline 'Shortened sleep duration linked to increased risk of heart disease'. Print Edition | Subscribe