This study will look at an alternative new pathway for diagnosis and treatment based on simple procedures in the patient's own home compared with the current conventional laboratory based pathway. The purpose is to determine whether all patients with OSA require the more elaborate laboratory procedures, or whether a subgroup can be managed more simply.

The research question we are exploring is whether the conventional approach is better in terms of successful treatment, compliance with treatment, and quality of life. There will be 2 arms to the study. Subject will be randomly assigned to either one of the following two treatment options: 1) the conventional investigation and nasal CPAP treatment pathway comprising 2 overnight sleep studies, one for diagnosis and one for determining the required level of nasal CPAP treatment 2) experimental pathway that uses a simplified home study (overnight oximetry), together with a machine that automatically adjusts the nasal CPAP pressure to the required amount, and a careful follow-up during the first 2 weeks of treatment.

Procedures: The study protocol will require the subject to complete the following procedures which are part of routine clinical practice: History and Physical Examination by a physician, Home Oximetry (This simple test involves wearing an oxygen probe gently wrapped around subject's finger during a night's sleep to continuously measure the amount of oxygen in blood and detect obstructions of subject's breathing. The probe is easily applied by the subject and requires no supervision), Spirometry (simple non-invasive breathing test), Standardized Sleepiness Questionnaires, Orientation and Education regarding nasal CPAP therapy, and compliance monitoring, Overnight polysomnography (This is the procedure that requires subject to spend a night in the sleep laboratory with a variety of painless and non-invasive monitoring devices attached to the body. The purpose is to obtain detailed information about subject's sleep quality, breathing, heart function, and body movements during sleep. Subject will be continuously monitored by a trained technologist during this procedure.). The following procedures are not routine and subject may be required to complete some or all of them depending on which pathway assigned to. Follow-up visits to the Clinic on Days 7 and 14 of nasal CPAP treatment for adjustments of nasal CPAP pressure as required (this could also be done at home), Repeat Home Oximetry as required, Quality of Life Questionnaire.

Inclusion Criteria:

Age > 18 years

• Residence in the Lower Mainland
• History and physical examination findings compatible with OSAHS
• Normal spirometry. (This is necessary to avoid decreased specificity of overnight oximetry attributable to underlying lung disease)
• Epworth Sleepiness Scale > 10

Exclusion Criteria:

• Age < 18 years
• Pregnancy
• Other known disorders that cause daytime sleepiness
• Requiring sedative/hypnotic medications
• Psychiatric disorder
• Life threatening co-morbidity e.g. chronic lung disease, coronary artery disease - unstable angina, recent myocardial infarction, heart failure, seizure disorder, and previous motor vehicle accident attributed to hypersomnolence
• Language barrier
• Inability to give informed consent
• Contraindication to nasal CPAP therapy
• Previous treatment of OSAHS with nasal CPAP, oral appliance therapy or corrective upper airway surgery.