Overnight Oximetry Pulse oximeters record oxygen saturation and heart rate levels of patients overnight. This is an easy self-administered test that is done from the comfort of your own home. It is a small easy to use oximeter device that consists of an oxygen sensor clipped to your finger. You sleep with the oximeter overnight and it records data continuously throughout the night. The data recorded measures your blood oxygen levels and results in a comprehensive report your physician will review. An overnight oximetry test is a useful tool used for determining if a patient has hypoxemia (abnormally low concentration of oxygen in the blood) and is in need of home oxygen, or if the patient is already on home oxygen therapy, they may need to increase or decrease their current levels. Overnight pulse oximetry testing not only determines the need for oxygen but also screens patients for signs of Obstructive Sleep Apnea (OSA). While it provides a limited amount of information for a complete diagnosis of obstructive sleep apnea, it is typically the first step in determining whether further in-lab testing or home sleep testing is needed to obtain proper diagnosis and treatment.