The purpose of this randomized prospective study is to compare the efficacy of two approaches to initiate Positive Airway Pressure (PAP) treatment in patients diagnosed as having obstructive sleep apnea (OSA) by portable monitoring (PM) (limited sleep study). One pathway involves attended Continuous Positive Airway Pressure (CPAP) titration by PSG (full attended sleep study) followed by CPAP treatment. The other pathway involves treatment with auto-adjusting positive airway pressure (APAP)(without a titration). Study Aims: Compare PAP adherence, improvement in subjective sleepiness (Epworth Sleepiness Scale), reaction time (Psychomotor vigilance test), quality of life by the Functional Outcomes of Sleep Questionnaire (FOSQ), and PAP satisfaction (PAP satisfaction questionnaire) between the two study arms.