When someone suggests that you re-think your lifestyle habits, you likely focus on your diet and exercise habits and maybe even your stress levels, as you make efforts to improve your health. Those are certainly areas in your life that directly impact your health, but one modifiable habit that could probably use some attention is your sleep habit. A new scientific statement from the American Heart Association suggests that short sleep or poor quality sleep may adversely affect your cardio-metabolic health, raising the risk of obesity, Type 2 diabetes, and heart disease, including hypertension.
Heart disease is the number one killer of men and women in the U.S. today, and cardiovascular disease is the number one cause of death globally. One in three adults in the U.S. has some form of heart disease. We know that genetics and lifestyle play a role in heart disease. We can’t change genetics, but we can change our lifestyle choices, which can minimize or sometimes even “zero out” genetic risk.
Clearly food choices and quantities can impact weight gain, and they can also raise the risk of developing artery clogging fat and central or abdominal obesity. Eating a diet rich in mono- and polyunsaturated fats and choosing mostly non-meat proteins like fish, beans, nuts, seeds, legumes, and eggs (egg whites) can help to limit heart disease. Because saturated fat is mostly found in animal-derived products, choosing fat free milk and nut milks as well as low fat and fat free yogurts and cheeses will also help to limit cardiovascular disease risk.
Exercise is a no brainer and the more the better. Commit to 30 or more minutes daily of aerobic exercise and also commit to weight training two or three days a week. Varying your routines will help you to stay challenged and burning calories.
Now let’s talk about sleep.
Sleep habits are a cornerstone of health. They have been identified as having a direct impact on cardiovascular (CVD) risk factors. Studies have confirmed that short sleep cycles of less than seven hours, and long sleep cycles of more than nine hours, are associated with increased risk of obesity, diabetes, and all-cause mortality. Obesity and diabetes are directly linked to increased CVD risk. We also know that poor sleep and short duration sleep are associated with impaired insulin sensitivity which in turn is linked to impaired lipid metabolism. In fact, short sleep combined with excess weight and sedentary lifestyle is a trifecta for increased risk of mortality from CVD disease.
Sleep disorders are also associated with an increased risk of heart disease. OSA (obstructive sleep apnea) is a risk factor for hypertension and is also linked to an increased risk of stroke, coronary heart disease and heart failure. Insomnia is linked to an increased risk of heart attacks.
In the AHA's new position statement mentioned above, the authors reviewed a large body of critical analyses of the relationship between poor or non-optimal sleep patterns and disorders and the impact on overall heart health. The authors noted the current common trend in the population of devaluing sleep as a critical component of overall health and heart health. The authors also cite the recent research that suggests poor sleep and its link to increased inflammation (elevation of pro-inflammatory cytokines), which can further exacerbate cardio-metabolic dysfunction. Their analysis concluded that poor sleep duration and poor quality sleep has a direct influence on cardio-metabolic risk factors and CVD.
Sleep and depression
Another consideration is how sleep impacts depressive symptoms and how depressive symptoms impact CVD. There is still much research to be done on the complicated interactions between diet, exercise, sleep, and the impact on vulnerable populations, like individuals who either have a higher risk of developing depression or already have depression and the interaction of that condition with CVD risk.
There were limitations to the many studies that this position paper reviewed, most notably the lack of quantitative sleep measures (sleep studies) that were not present in some of the long cohort studies. Another problem was that many of the studies did not factor in socio-demographics, household, community, and cultural factors that might influence self-reporting on sleep habits. Future studies should use direct sleep measurements, and because daytime napping has become more prevalent, especially at worksites, that habit needs to be addressed in studies that look to evaluate sleep’s impact on CVD risk. The research needs to include 24-hour habits and not just nighttime sleep habits.
Similar to the Centers for Disease Control and Prevention’s map of the “stroke belt and CVD risk atlas,” a geographic area in the southern region of the U.S. that is designated as at “higher risk of stroke because of their high prevalence of obesity,” we may someday see a “sleep belt or atlas” that suggests poor sleep habits and heightened risk of CVD across a particular area of the U.S. I suspect it may even be larger than the stroke belt given the lack of importance that most people give to their sleep habits.
Eli Hendel, M.D. is a board-certified Internist and pulmonary specialist with board certification in Sleep Medicine. He is an Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, Qualified Medical Examiner for the State of California Department of Industrial Relations, and Director of Intensive Care Services at Glendale Memorial Hospital. His areas of expertise in private practice include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases.