An 18-year Follow-up Study on OSA in a Population-based Cohort

Inclusion Criteria: \- Subjects participants from the 2003 cohort Exclusion Criteria: * Neuromuscular disease * Pathological central apnoea * Severe chronic lung disease with documented hypoxaemia or awake oxygen saturation \<92% * Chronic respiratory failure (unrelated to OSA) * Acquired upper airway disease/obstruction * Craniofacial abnormalities (e.g. secondary to trauma and malignancy) Other arrangement: * Subjects who have any respiratory illness within 2 weeks of the scheduled follow-up visit will have their assessment re-arranged until they have fully recovered. * Subjects taking medications that may affect sleep, upper airway patency or blood pressure (for example sedatives, stimulants, antihistamines, and cough medicine) within a week from recruitment will also be rescheduled to participate when they are free from medication use for at least 2 weeks. * Subjects with hypertension and are on anti-hypertensive therapy are allowed to continue on their medication and the information will be obtained and recorded during data collection.