To sleep provides more than a chance to dream. Scientists are waking up to the fact that the right amount of shut-eye restores bones, gives the brain a much-needed break from the daily grind, and prevents a whole host of maladies, including heart disease. In 2007, British researchers reported that snoozing five hours or less every night doubles a person's risk of developing a cardiovascular illness. Here are a few other reasons more quality sack time should be priority No. 1 for the 63 percent of Americans who get less than eight hours of sleep each night:

A lack of Z's can clog your arteries. An article in a recent issue of the Journal of the American Medical Association claimed that study subjects who slept five hours or less were more likely than their better-rested peers to accumulate calcium deposits in their coronary arteries, a condition that can make the arteries less flexible and lead to heart disease. Researchers concluded that those who got less than the recommended eight hours every night could cut their calcification risk by a third and enjoy a blood-pressure drop as great as 16.5 points if they added just one hour of sleep to their nightly routine.

That overnight dip in blood pressure goes a long way in helping heart-disease patients. A study of 1,255 Japanese adults diagnosed with high blood pressure found that those who got less than seven and half hours of slumber were almost twice as likely to suffer and/or die from a cardiac event such as a heart attack; that risk was doubly greater for patients who slept for only brief periods of time and were prone to the riser pattern, in which blood pressure remains elevated even during non-REM sleep, when it usually drops.

The chronically sleep deprived stand a greater chance of heart disease via diabetes and/or obesity. A deficit of restful slumber has been linked to diabetes and obesity, two conditions that also have ties to cardiovascular illnesses since insulin resistance and inflammation play a major role in the deterioration of the cardiovascular system. Researchers at the University of Chicago observed that after less than one week of getting just half of the standard eight hours sleep a night, test subjects exhibited changes in endocrine function and glucose tolerance that suggested the early stages of diabetes. They also determined that sleep deprivation caused the levels of leptin in the blood to decrease resulting in an increase in appetite.