That difference was still significant even when the data is corrected for known risk factors such as smoking, blood pressure, diabetes and obesity, Morris says.
C-reactive protein is used extensively as a marker of inflammation and heart disease risk. People whose C-reactive protein levels are in the upper third of the population (above 3 milligrams per liter) have roughly double the risk of a heart attack, compared with people with lower C-reactive protein levels, according to the American Heart Association and Centers for Disease Control and Prevention.
"For people who got little sleep, the C-reactive protein levels were increased, but still in the range of what health authorities would consider low to intermediate risk," she says. "However, our study population represents a community-based population [as opposed to patients in the hospital or with known cardiovascular disease], so they have overall lower risk and lower C-reactive protein levels than many of the high risk populations in other studies."
Inflammation may be one way poor sleep quality increases the risks for heart disease and stroke, Morris says.
"It remains uncertain whether short sleep duration contributes directly to cardiovascular mortality, or whether it is a mediating or moderating factor," she says.
Previous research has shown that people who sleep between seven and eight hours per night live longest, and that especially short or especially long sleep durations bring higher mortality. Researchers find that short and long sleep durations are often seen together with high blood pressure, obesity, diabetes and psychological stress all risk factors for heart disease and stroke.
Long sleep duration may reflect a compensation for sleep apnea, which the sleep quality survey do
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