Smoking, high cholesterol, hypertension and obesity are among the known risk factors for carotid artery stenosis, the narrowing of the arteries that supply the brain with blood, and whose blockage can lead to stroke. Now researchers may have found a new risk: heavy snoring. An Australian study had 110 volunteers, men and women 45 to 80 years old, spend the night in a sleep laboratory. Researchers timed their snoring, and used ultrasound to measure the extent of plaque in their arteries.