Researchers at the University of Chicago Medical Center have found even one extra hour of sleep each night appears to decrease the risk of coronary artery calcification-- which is associated with heart disease.
Out of 495 study participants, 27-percent of those who had calcified arteries slept less than five hours a night.
That number dropped to 11-percent for those who slept five to seven hours and just six percent for participants who got even more shut-eye.
Researchers say they don't know why there was such a difference.
They say more studies are needed.