People who scrimp on sleep are more likely to develop hardening of their arteries, a precursor to heart disease, research suggests. Calcified arteries were found in nearly a third of people who slept fewer than five hours a night. This dropped to around one in 10 for those who slept an extra hour, the Journal of the American Medical Association study of 495 adults found. Experts said getting enough sleep was important for good heart health. In the study, the volunteers underwent two CT scans, designed to assess the build-up of calcium in the heart's arteries, five years apart.