According to a study published in the American Journal of Epidemiology titled "Increased Prevalence of Sleep-disordered Breathing in Adults," 5.9 million American adults have been diagnosed with sleep apnea, but 23.5 million remain undiagnosed.
Sleep apnea has made headlines in recent years, bringing awareness to the dangers of the condition. For example, when actress Carrie Fisher died last year, sleep apnea was listed as one of the leading causes of death.