"The groundwork of all happiness is health." - Leigh Hunt

Too much or too little sleep is linked to stiff arteries.

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The research we're taking a look at.

According to a study of greater than 47,000 apparently healthy young and middle-aged adults, those that slept an excessive amount of or too little were more prone to have early signs of heart disease.

Study volunteers filled out sleep questionnaires and underwent tests to evaluate their heart and leg arteries. Researchers found that individuals who slept nine or more hours per night had more calcium deposits within the partitions of their heart arteries and within the arteries of their legs than those that slept seven hours. These early signs of heart disease were also more common in individuals who slept five or fewer hours per night and in those that reported poor sleep quality.

The authors, whose study was published online Sept. 10. Atherosclerosis, thrombosis, and vascular biology, note that many studies have linked insufficient sleep to hypertension and other aspects that increase the chance of heart disease. It is less clear how excessive sleep may contribute to early heart disease. One possibility is that individuals who sleep longer than usual could have fragmented sleep, which may increase levels of inflammation, a known risk factor for heart disease.