A CPAP Titration is required if sleep apnea is diagnosed or strongly suspected. Typically, this is a full night of study performed during a second night, but is sometimes performed during the last few hours of a split-night study.  During the titration study, the technician will set the air pressure on the CPAP at a certain level and then watch the resulting measurements. If that pressure does not reduce the number of apnea and hypopnea events, or eliminate the snoring, the technician will adjust the air pressure and continue observation. This process continues throughout the night until the optimum pressure is reached.