Researchers say sleep deprivation may increase the risk of heart disease. People who get five to seven hours of sleep nightly are almost twice as likely to develop early signs of blood-vessel damage as those who get more rest, according to a five-year study published in the Journal of the American Medical Association last week.
Those who sleep less than five hours a night are at even higher risk, said Bloomberg News, reporting on the study.
Earlier studies had showed that abnormal sleep patterns skew the release of appetite-related hormones, which may contribute to obesity and diabetes. The latest research is the first to suggest a shorter night's sleep may have a more direct and damaging effect on heart health, said Diane Lauderdale, the University of Chicago epidemiologist who led the research team.
"There's mounting evidence that really short sleep duration, as in less than five hours a night, may well have health consequences," she told Bloomberg. "It's pretty safe to say that it's a good idea to get more than five hours of sleep a night."
Heart disease often occurs after years of damage to the blood vessels that surround and support the cardiac muscle. A key step in the damage occurs when deposits of calcium build up on blood-vessel walls, setting the stage for the growth of plaque laden with fat, clotted blood and immune cells.
Smoking, diabetes, high blood cholesterol and obesity have all been linked directly to calcium build-up in the coronary arteries around the heart. The study involved 495 people aged 35 to 47, who did not have existing heart damage, to see whether insufficient sleep might also be a contributing factor.
The largest group of subjects got five to seven hours of sleep a night. In the five years of the study, about 11 per cent of them developed calcified arteries. With less than five hours of nightly sleep, the danger rose starkly, with 27 per cent of people developing blood-vessel calcification during the study.
In contrast, only 6 per cent of those who got more than seven hours of sleep a night showed signs of heart damage by the study's end.
This story was first published in Mind Your Body, The Straits Times, on Jan 1, 2008.
