Gender influences poor sleep impact in heart patients
medwireNews: Poor sleep, particularly waking too early, appears to be associated with unhealthy rises in inflammation levels in women with coronary heart disease (CHD), findings from the Heart and Soul study indicate.
The results also highlight important gender differences in the effects of poor sleep, given that there was no association between poor sleep and inflammation among men with the heart condition.
"Inflammation is a well-known predictor of cardiovascular health," lead researcher Aric Prather (University of California, San Francisco, USA) said in a press statement. "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."
The researchers measured sleep quality and markers of inflammation, including circulating levels of interleukin (IL)-6, high-sensitivity C-reactive protein (CRP), and fibrinogen, in 980 participants with CHD at baseline and in 626 (112 women) after 5 years.
At baseline, the average Pittsburgh Sleep Quality Index (PSQI) score was 1.8 out of a possible 4, and 36.0% of participants reported difficulty falling asleep, 79.5% reported waking frequently, and 44.9% reported waking too early.
Overall, subjective sleep quality was not associated with inflammatory markers at baseline or with changes in these markers over 5 years of follow up, but after stratifying for gender, significant associations were found for women but not men.
After adjusting for a number of covariates, such as sociodemographic characteristics, lifestyle and psychosocial variables, medical comorbidities, medication use, and cardiac function, poorer PSQI subjective sleep quality at baseline was significantly associated with 5-year increases in IL-6, CRP, and fibrinogen in women.
Waking too early, specifically, was a significant predictor of 5-year increases in circulating IL-6 and fibrinogen, but only the association with IL-6 remained significant after adjusting for covariates.
"These results add to growing evidence that increased inflammation may contribute to the negative cardiovascular consequences often associated with poor sleep, indicating poor sleep quality," the researchers write in the Journal of Psychiatric Research.
Commenting on the lack of association between poor sleep and inflammation in men, they say "it is possible that testosterone, which is at higher levels in men, served to buffer the effects of poor subjective sleep quality on 5-year changes in inflammation."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lucy Piper, Senior medwireNews Reporter