People who sleep poorly or do not get enough sleep have higher levels of inflammation, a risk factor for heart disease and stroke, researchers have found.

The results come from surveying 525 middle-aged people participating in the Morehouse-Emory Partnership to Eliminate Cardiovascular Health Disparities (META-Health) study on their sleep quality and sleep duration.

In the META-Health study, the researchers assessed sleep quality using the Pittsburgh Sleep Quality Index survey, where a score over six (based on the median sleep score of the study population) is considered poor. They also analyzed their data based on hours of sleep.

Individuals who reported 6 or fewer hours of sleep had higher levels of three inflammatory markers: fibrinogen, IL-6, and C-reactive protein. In particular, average C-reactive protein levels were about 25% higher (2 milligrams per liter compared to 1.6) in people who reported fewer than 6 hours of sleep, compared to those reporting between 6 and 9 hours.

That difference was still significant even when the data is corrected for known risk factors such as smoking, blood pressure, diabetes, and obesity, said Alanna Morris, MD, a cardiology fellow at Emory University School of Medicine. Morris presented data from the study at the American Heart Association Scientific Sessions in Chicago on November 14.