Poor-quality sleep may affect heart health

Research indicates that poor-quality sleep—and waking too early in particular—is associated with increased inflammation among women with heart disease. There was no similar association found for men, suggesting that women with heart disease and sleep problems may be at particular risk for inflammation that can be damaging to the heart.
Researchers at the University of California San Francisco investigated the relationship between sleep quality and inflammation linked to coronary heart disease. They also sought information about how an association between sleep and inflammation might differ between men and women. Their investigation included 980 men and women at the outset, and 626 completed the 5-year study. All of those included were suffering from coronary heart disease. The average age of men in the study was 66. Women were slightly younger, with an average age of 64. Researchers measured sleep quality by asking participants to rate their sleep over the previous month. They also asked for reports of some of the most common sleep problems, including difficulty falling asleep, difficulty staying asleep, waking frequently throughout the night, and waking too early in the morning. Researchers assessed inflammation levels using 3 biomarkers: Interkeukin-6, C-reactive protein, and Fibrinogen.
After 5 years, researchers repeated tests for inflammation and once again sought reports on sleep quality and sleep problems. When they analyzed data for both men and women together, researchers found no links between inflammation and sleep quality. However, when they analyzed data taking gender into account, researchers found a relationship between inflammation and sleep existed for women, but not for men:

• Women who reported poor sleep quality experienced greater increases in levels of inflammation over the 5-year period than men.
• Women who reported their sleep quality as “very poor” or “fairly poor.” experienced increases to their inflammation markers that were 2.5 times greater than men who reported the same levels of poor sleep.
• The association between inflammation and sleep remained intact for women even after taking into account other factors that might influence inflammation, including age, cardiac function, body mass index, medication use, and lifestyle factors.
• The link between inflammation and sleep for women with coronary heart disease was particularly strong among those women who had a tendency to wake too early in the morning.
• Women were more likely than men to report waking too early. They were slightly more likely than men to report waking frequently during the night and having difficulty falling asleep.
• Because the majority of women in the study were post-menopausal, researchers hypothesized that low estrogen levels might explain the link between poor sleep and inflammation. This question was not examined in the study itself.