Men who sleep less than six hours a night may be at an increased risk of cardiovascular disease compared to those who sleep between seven and eight hours, a new study suggests.

The study showed that poor quality sleep of less than six hours increases the risk of atherosclerosis by 27 per cent compared to seven to eight hours of sleep. Atherosclerosis refers to the build-up of fats, cholesterol and other substances in and on the artery walls throughout the body.

On the other hand, women who slept more than eight hours a night had an increased risk of atherosclerosis. "Cardiovascular disease is a major global problem and we are preventing and treating it using several approaches, including pharmaceuticals, physical activity and diet," said Jose M. Ordovas, researcher at the Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) in Madrid. 

"But the study emphasizes we have to include sleep as one of the weapons we use to fight heart disease -- a factor we are compromising every day," he added.

For the study, published in the Journal of the American College of Cardiology, the team included 3,974 bank employees among which all were without known heart disease and two-thirds were men. In addition, alcohol and caffeine consumption were found to cause short and disrupted sleep. 

"Many people think alcohol is a good inducer of sleep, but there's a rebound effect. If you drink alcohol, you may wake up after a short period of sleep and have a hard time getting back to sleep. And if you do get back to sleep, it's often a poor-quality sleep," Ordovas said. Lack of sleep has been known to raise the risk of cardiovascular disease by increasing heart disease risk factors such as glucose levels, blood pressure, inflammation and obesity.