AIR is a non-interventional sleep apnoea registry. The registry ligates with experts, interested sleep physicians, researches in sleep medicine etc across the nation to enrol as a site in the registry. Each site will fill the online questionnaire at the baseline which will capture basic patient information as well as the polysomnography test results. Each sleep raw data will be specifically verified by the central scoring site, Gurgaon. Appropriate feedback would be provided to the site about the quality of their data. Similarly, an annual follow up will be undertaken after a year for each patient being recruited in the study.