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A version of this post recently appeared on the Robert Wood Johnson Foundation Human Capital Blog
Heart disease accounts for 1 in every 4 deaths in the United States- 600,000 deaths per year. While prevention and treatment regimens for heart disease include important changes in lifestyle, centering primarily on improvements in diet and exercise, sleep is rarely part of this discussion. This is alarming given the growing evidence from large-scale population studies and laboratory-based experiments that sleep plays a larger role in heart health than originally appreciated by the medical community. For example, in a 2003 study, women with established coronary heart disease who reported poor sleep quality were more than 2.5 times more likely to go on to experience a cardiac event than good quality sleepers. Nevertheless, when it comes to asking patients about their sleep, health care providers routinely hit the snooze button.
In an effort to raise the profile of sleep as a risk factor for cardiovascular disease (CVD), my work has focused on investigating the links between sleep and the biological pathways implicated in CVD development and progression. Said another way, much of my research focuses on how sleep disturbance "gets under the skin". In a recent study, we focused on a sample of nearly 700 midlife adults with coronary heart disease who were followed over 5 years. We found that compared to women who reported good quality sleep, women with poor sleep quality, particularly complaints of waking up too early in the morning, showed greater 5-year increases in several markers of inflammation, including interleukin-6 (IL-6), fibrinogen, and C-reactive protein, all of which are well known to contribute to coronary heart disease progression. This prospective association remained statistically significant after controlling for many other important variables, such as age, body mass, medication use, other medical conditions, and depressive symptoms. Interestingly, sleep quality was unrelated to changes in inflammation among men. This is consistent with several other cross-sectional findings, raising questions about why women may be preferentially susceptible to the ill effects of poor sleep. Right now we don’t have a good answer- it could be due to differences in sex hormones, like estrogen or testosterone, both of which have effects on inflammatory activity. Alternatively, the experience of sleep quality may have a different meaning for women compared to men. On this point, when men and women have their sleep measured in a controlled sleep laboratory, men objectively show poorer sleep but women are more vocal about sleep complaints.
A need to bring sleep into the health behavior discussion
If the explosion of research linking sleep and heart health tell us one thing, it is that sleep deserves a place in the discussion of health behaviors, along side exercise and diet, for improving health and well-being and preventing heart disease. Our recent research suggests that sleep is certainly relevant to women with coronary heart disease; however, there are a myriad of studies showing that sleep affects physical health in men and women equally.
Sleep is a commodity in short supply in the United States as highlighted by a recent report from the Center for Disease Control and Prevention that labeled insufficient sleep as a public health epidemic. With all of the growing research evidence on this topic, it is my hope that continues to gain traction both in the doctor’s office and at the policy level. Discussions of sleep hygiene and the use of empirically based sleep treatments can address sleep complaints of the individual, but a larger policy discussion is needed to combat the sleep disparities observed at the societal level. Indeed, our work is cut out for us, but I won’t let it keep me up at night (or at least I’ll try my best).
