Short sleep duration increases cardiovascular risk

Poor sleep quality and reduced sleep duration have been linked to an increased risk of cardiovascular disease, as they increase heart disease risk factors such as glucose levels, blood pressure, inflammation and obesity. However, large clinical studies that investigate the link between measured sleep and atherosclerosis — the build-up of plaque which is made up of fat, cholesterol, calcium and other substances in artery walls — has been lacking.

The researchers also noted that a shorter sleep duration that is of good quality can overcome the detrimental effects of shorter sleep.

To investigate this, researchers conducted a study that involved 3974 participants from the PESA (Progression of Early Subclinical Atherosclerosis) study. All participants were known not to have any heart disease and were 62.6 per cent men. The participants wore an actigraph — a small device which continuously measures activity or movement — for seven days to measure their sleep. The participants were divided into four groups: those who slept less than six hours, those who slept six to seven hours, those who slept seven to eight hours and those who slept more than eight hours. The researchers also looked for signs of heart disease in participants through the use of 3D ultrasound and cardiac CT scans.

The researchers found that when they adjusted for traditional risk factors for heart disease, participants who slept less than six hours were 27 per cent were more likely to have atherosclerosis throughout the body compared with those who slept seven to eight hours. The researchers also found that those who had poor quality sleep were 34 per cent more likely to develop atherosclerosis compared to those who had good quality sleep. Quality of sleep is defined by how often a person wakes up during the night and the frequency of movement during sleep which reflects the sleep phases. The study found that alcohol and caffeine consumption were higher in participants with short and disrupted sleep. The study also found that the small number of women who slept more than eight hours a night had an increased risk of atherosclerosis. The researchers also noted that a shorter sleep duration that is of good quality can overcome the detrimental effects of shorter sleep.

This large study on a healthy population, unlike other studies, obtains an objective measure of sleep with the help of an actigraph rather than the self-reported state of sleep as done in previous studies. It goes on to show that people who sleep less than six hours a night and poor quality of sleep can result in an increased risk of atherosclerosis.

Source: Journal of the American College of Cardiology