Obstructive sleep apnea are periods of breathing cessation that occurred during sleep when tissue obstructs the airway. Since it only occurs during sleep, anatomical studies such as CT or MRI or visualization studies such as bronchoscopy or nasal endoscopy do not help make the diagnosis. The diagnosis of obstructive sleep apnea requires polysomnography. Polysomnography or a polysomnogram is more commonly known as an overnight sleep study. The patient comes to sleep lab, is connected to several monitors that assess oxygenation, sleep cycles, and respirations among others. Once diagnosed, patients may return to the sleep lab to titrate continuous positive airway pressure (CPAP) settings for sleep apnea treatment. A Holter monitor is used to detect cardiac rhythm abnormalities and is essentially a chronic electrocardiographic (ECG) rhythm strip.