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. Data from the study are presented Sunday in Chicago by Doctor Alanna Morris, a cardiology fellow at Emory University School of Medicine.
Acute sleep deprivation leads to an increased production of inflammatory hormones and changes in blood vessel function, but more research is needed on the physiological effects of chronic lack of sleep, Morris says.
"Most of the studies looking at the body's response to lack of sleep have looked at subjects who have been acutely sleep deprived for more than 24 hours in experimental sleep laboratories," she says. "Nothing of this sort has been investigated in epidemiologic studies."
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 six 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 percent higher (2 milligrams per liter compared to 1.6) in people who reported fewer than six hours of sleep, compared to those reporting between six and nine hours. 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 as a marker of inflammation and heart disease risk. People whose C-reactive protein levels are in the upper third of the population have roughly double the risk of a heart attack. "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, so they have overall lower risk and lower C-reactive protein levels than many of the high risk populations in other studies."
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.
MEDICA.de; Source: Emory University