Poor sleep appears to contribute to the progression of heart disease in women by raising their inflammation levels, but this effect was not seen in men, researchers say.
"Inflammation is a well-known predictor of cardiovascular health," lead author Aric Prather, a clinical health psychologist and assistant professor of psychiatry at the University of California, San Francisco, said in a university news release.
"Now we have evidence that poor sleep appears to play a bigger role than we had previously thought in driving long-term increases in inflammation levels and may contribute to the negative consequences often associated with poor sleep," Prather added.
Previous research has shown that sleeping fewer than six hours per night may raise the risk of chronic health problems, including heart disease, and is associated with higher levels of inflammation.
This new study included nearly 700 men (average age 66) and women (average age 64) with coronary heart disease. Among the women, poor sleep quality was significantly associated with increases in markers of inflammation over five years. However, this was not the case among men.
Most of the women in the study were postmenopausal and their lower levels of estrogen could help explain the link between poor sleep and higher levels of inflammation, the study authors suggested.
"It is possible that testosterone, which is at higher levels in men, served to buffer the effects of poor subjective sleep quality," Prather's team wrote in the study published online June 5 in the Journal of Psychiatric Research.
The researchers said their findings reveal potentially important gender differences and provide evidence that increased inflammation may be a major way that poor sleep contributes to the progression of heart disease in women.
Although the study found an association between self-reported poor sleep quality and increased signs of inflammation among older women with heart disease, it did not prove a cause-and-effect relationship.