The black under-eye rings aren’t the only negative effect from too little sleep. Insufficient shut-eye has been associated with a number of chronic diseases and conditions, as well, including diabetes, anxiety, obesity and depression. Now, researchers have found such a strong link between lack of zzzs and calcium buildup in the heart, that it may have some of you hiding under the covers.

Published in the latest Journal of the American Medical Association, researcher at the University of Chicago followed the sleeping habits of 495 healthy volunteers ages 35 to 47. Participants were given an MRI at the beginning and end of the five-year study. To measure their snooze amount, the volunteers wore a device on their wrists called an actigraph, which measured their movements day and night (being very still usually meant they were asleep).

After five years, the volunteers who averaged five or fewer hours of sleep were 4.5 times more at risk of heart disease — which is the No. 1 cause of death in women each year.

Among the lack-of-sleep group, 27 percent of them developed coronary artery calcification over the five-year follow-up, Diane Lauderdale, the study’s lead author said, NPR reports. And among the people who slept seven hours or more, on average, six percent developed coronary artery calcification. To make sure it was shut-eye making all the difference, the researches subtracted out the effects of other known coronary risk factors, such as high cholesterol, high blood pressure, diabetes and smoking.

The Chicago researchers did not conclude how shut-eye was linked to clogged arteries.

It is known that sleep could affect certain hormones and chemicals in the body – including cortisol, a stress hormone, and leptine, which regulates body weight and metabolism.

Do you have trouble getting a good night’s rest?

Web MD offers ten tips to promote shut-eye. Three of them include:

• Avoid napping. Napping can only make matters worse if you usually have problems falling asleep. If you do nap, keep it short. A brief 15-to-20-minute snooze about eight hours after you get up in the morning can actually be rejuvenating.
• Keep pets off the bed. Does your pet sleep with you? This, too, may cause you to awaken during the night, either from allergies or pet movements. Fido and Fluffy might be better off on the floor than on your sheets.
• Avoid watching TV, eating and discussing emotional issues in bed. The bed should be used for sleep and sex only. If not, you can end up associating the bed with distracting activities that could make it difficult for you to fall asleep.

Click here for more sleep advice.

Tell us: How many hours of sleep do you need each night?