If you don't want to suffer the fate of hardened (calcified) arteries which also lead to cardiovascular diseases (hypertension of high blood pressure), do not skimp on restful sleep. According to a study led by Dr. Diane Lauderdale of the University of Chicago, getting enough sleep is important for good cardiovascular health. In the study, the researchers subjected to 2 CT scans to access the built-up of calcium in the arteries five years apart. In the first CT scan, none of the subjects had any calcification in their arteries, but the picture changed 5 years later with 61 of them showing calcification in their arteries. Calcification was least among those who regularly sleep more than 7 hours and greatest for those who sleep less than 5 hours nightly.
Possible explanation - high blood pressure increases calcification and blood pressure is lowered during sleep. So less sleep may lead to more hours of high blood pressure and therefore calcification, while the reversed is true for more sleep.
Another possible explanation may be stress hormones like cortisol which is related to decreased sleep and increased calcification.