The prevalence of obstructive sleep apnea (OSA) in patients admitted to the hospital is likely significantly higher than the general population as hospitalized patients carry a high prevalence of co-morbid conditions, such as diabetes and cardiovascular diseases, that are commonly associated with OSA. The true prevalence of OSA in hospitalized patients is not known, though there is limited data suggesting that the rate of OSA in hospitalized patients is indeed high. Two studies have reported on the rate of polysomnographic (PSG) diagnosis of OSA in patients referred for OSA evaluation while in-hospital. These studies reported frequencies of 77% (in a retrospective study of 100 patients) and 88-100% (in an observational study of 250 patients). Similarly, 2 studies evaluated the prevalence of sleep disordered breathing in patients admitted with acutely decompensated heart failure, finding frequencies of sleep apnea in 97% (prospective study of 29 patients studied with PSG) and 75% (prospective study of 395 consecutive patients studied with portable monitors). However, all of these studies are limited by either study design (retrospective), small numbers, limited channel portable monitoring, or evaluations of highly select patient populations. Furthermore, none of these studies examined screening tools that may help to identify which patients are at risk for OSA and thus might require the more extensive and expensive objective testing.