Skipping sleep may promote the thickening of coronary arteries and increase the risk of heart disease, a new study suggests. Researchers at the University of Chicago Medical Centre in the US have found that people who, on an average, sleep less have a greater chance of developing thickened arteries than people who sleep longer.
The benefit from just one hour of extra sleep per day is similar to the gain available from reducing blood pressure by 16mm, according to the study, to be published tomorrow in the Journal of the American Medical Association.
The researchers detected thickened arterial deposits in 6 per cent of people who slept more than seven hours a night, in 11 per cent of people who slept between five and seven hours, and in 27 per cent of people who slept less than five hours.
“The magnitude of the difference was a surprise,” said Diane Lauderdale, associate professor at the University of Chicago Medical Centre’s department of health studies and the study’s director.
“It’s also a mystery. We can only speculate about why those with shorter average sleep duration were more likely to develop the calcification [thickening] of the arteries.”
“This is a large and dramatic effect,” said Batmanabhan Gitanjali, head of a sleep disorders laboratory at the Jawaharlal
Nehru Institute of Postgraduate Medical Education and Research, Puducherry, who was not associated with the study.
The study examined the sleep habits and coronary arteries of 495 men and women between the ages of 35 and 47 over a five-year period. None of the volunteers had any deposits in their arteries at the start of the study.
It revealed a 33 per cent lowered risk of arterial thickening even after the scientists adjusted data to cancel out the effects of other factors that could contribute to arterial thickening such as smoking, age, sex, race and education.
“But we’ll need to validate these findings through larger studies to understand what’s going on,” said Batmanabhan Gitanjali
One current idea among sleep medicine specialists is that healthy people may display a range of sleep habits. Short-sleepers could do with five hours of sleep while long-sleepers are comfortable sleeping eight hours or more.
A number of previous studies have shown that chronic lack of sleep is associated with a number of other risk factors linked to heart disease — weight gain, diabetes and even high blood pressure.
Lauderdale and her colleagues say the stress hormone called cortisol or some as yet unidentified factor may reduce sleep and increase arterial thickening.
Another possible mechanism may involve the blood pressure. Blood pressure decreases during sleep, so people who sleep less during a 24-hour cycle may have higher blood pressure which can contribute to the arterial thickening.
“This study does not prove that short sleep leads to coronary artery disease, but it is safe to recommend at least six hours of sleep a night,” said Lauderdale.
Sources: The Telegraph (Kolkata, India)