A Split Sleep Study is performed to diagnosed Obstructive Sleep Apnea.and then to determine the correct Cpap pressure setting. During this study you will be connected to a computerized Cpap device that is managed by the Respiratory Technician. All the sensors used during the PSG study are utilized during this test as well. The pressure first begins at the lowest level and then gradually increases until the airway obstruction is resolved. Cpap can be ordered based on these settings. The advantages are that only one test can provide the same the same information as the two individual tests. (CPAP & Titration study). The disadvantage is that some patients never get into deep sleep before the titration study Because of the reduced sleep time available for dianostic portion of the test, the results can sometimes underestimate the severity of condition.