The NIH’s National Heart, Lung, and Blood Institute estimates that 12 million adult Americans are experiencing sleep apnea, many of them without even being aware that they suffer from this life-threatening illness.
In sleep apnea, or sleep-disordered breathing, the person’s upper airway closes and he or she actually stops breathing for brief intervals (from 10 to 30 seconds) repeatedly during sleep. In severe instances, this can occur as often as 30 times an hour.
Almost 10 percent of women and fully 25 percent of men are affected. More than two thirds of patients with obstructive sleep apnea are obese, as excess upper body fat can constrict the air-passageways and lungs. Recent research suggests that as many as 87 percent of obese people may suffer from undiagnosed sleep apnea.
Doctors and researchers have recognized for some time that people with sleep apnea are more likely to suffer from a variety of life-threatening conditions, including obesity, high blood pressure, heart failure and stroke. Until now, however, no research had quantified the extent to which sleep apnea increases the risk of death.
The Sleep Heart Health Study
Recently a research team led by Dr. Naresh Punjabi of Johns Hopkins University in Baltimore studied the cases of 6,441 men and women who were participating in the Sleep Heart Health Study (SHHS). Sponsored by the National Heart, Lung, and Blood Institute, SHHS is a cooperative longitudinal epidemiologic study being conducted by 16 universities and medical research centers to learn whether sleep-disordered breathing is associated with higher rates of coronary heart disease, stroke, all-cause mortality, and hypertension.
The SHHS study design is a prospective cohort study, that is, participants were enrolled at the outset and their case histories were tracked from that time forward over the course of several years. In the study group, about 33 percent of men had mild sleep apnea, almost 16 suffered moderately, and 8.2 percent were diagnosed with severe sleep apnea. Rates among women were consistently lower. Only 25 percent overall had mild sleep apnea, 8 percent had a moderate level, and just 3 percent had severe apnea.
Sleep Apnea and Mortality Rates
Dr. Punjabi’s research team was examining specifically the question of whether sleep-disordered breathing is associated with higher rates of death from any cause (all-cause mortality) in adults. They found that mild cases of sleep apnea involved no significant increased risk of death in either men or women. However people with severe sleep apnea had a significantly higher risk of death from any cause—1.5 times greater, in fact.
When broken down by age and sex, the mortality risk was found to be highest in men between the ages of 40 and 70 with severe sleep apnea. The men in this group were twice as likely to die from any cause as other men in that age range who did not experience sleep apnea. For men, though not for women, sleep apnea is also associated with increased risk of death due to coronary heart disease in particular.
These results confirm the importance of seeking a medical diagnosis and treatment for anyone who suspects they may be experiencing sleep apnea. Prominent symptoms include loud snoring, nighttime choking spells, heartburn, urination, sweating, chest pain and restlessness, morning headaches, and fatigue or excessive sleepiness during the day.
Sleep apnea is a treatable condition. For people who are obese—and they at the highest risk for developing sleep apnea—weight loss is in many cases the first choice for reducing and even eliminating this life-threatening condition.
The full report of Dr. Punjabi’s team is available here.
“Sleep-Disordered Breathing and Mortality: A Prospective Cohort Study,” by Naresh M. Punjabi, Brian S. Caffo, James L. Goodwin, Daniel J. Gottlieb, Anne B. Newman, George T. O’Connor, David M. Rapoport, Susan Redline, Helaine E. Resnick, John A. Robbins, Eyal Shahar, Mark L. Unruh, Jonathan M. Samet. PLoS Medicine.