Diagnostic sleep studies are used for the sleep tech on duty to observe what is happening during your sleep, documenting anything that would show you have sleep apnea. The diagnostic sleep study measures your nighttime sleep patterns. After you are connected to various leads and sensors, which allow the sleep tech to record and monitor your sleep, the sleep tech will observe you remotely throughout the night. Leads are placed on your scalp and face. A sensor on your finger monitors the oxygen level in your blood. Belts around your chest and belly measure your breathing. Small pads on your chest record your heart waves. After lights-out, you will not be disturbed for the remainder of the night.