The bidirectional link between sleep and pain is a widely accepted concept. While there has been much focus on this in recent years, studies investigating obstructive sleep apnoea (OSA) and chronic pain are still not very common, especially in context of continuous positive airway pressure (CPAP) therapy. In this study, people recently diagnosed with OSA, a common sleep disorder, that are receiving a CPAP mask are asked to fill in questionnaires at baseline, 3- and 6-month follow-up. Data of people with and without chronic pain will be collected and we will use the data will allow us to answer a number of clinically relevant questions. The primary questions investigate the following: 1) The association of CPAP adherence and pain outcomes with CPAP therapy at 3-month follow-up; 2) The association of baseline Apnoea-Hyopnea-Index on pain outcomes with CPAP therapy at 3-month follow-up. Secondary questions investigate the relevance of co-morbid insomnia (COMISA), the influence of chronic pain on CPAP adherence and general clinical outcomes of CPAP therapy in people with chronic pain.